title: Velocity

paragraphs: Velocity is a measure of how fast something moves in a particular direction. To define it needs both magnitude and direction. If an object moves east at 9 metres per second (9m/s), then its velocity is 9 m/s to the east.

paragraphs: The idea behind this is that speed doesn't tell us in which direction the object moves in a given frame of reference. Speed is one part of velocity, direction is the other part. Depending on the frame of reference, the velocity can be defined with many mathematical concepts required for making the correct analysis.

paragraphs: To calculate the average velocity of an object, we divide its displacement (its change of position) by the time it took to change position.

paragraphs: For example, if an object moves 20 meters (m) to the left in 1 seconds (s), its velocity (v) would be equal to:

paragraphs: Unlike average velocity, the instantaneous velocity tells us how fast something is moving at only one time, because velocity can only change with time.

paragraphs: The concept of velocity allows us to consider two different means of calculating the velocity. Two-dimensional motion "requires" us to use vector notation to define the physical quantities found throughout the kinematics.

paragraphs: where: formula_5is the total distance traveled in a given time interval formula_6. Each of these quantities can be calculated by substracting two different values intertwined within the given quantity, hence formula_7give the desired formula_8.

paragraphs: Contrary to average velocity, the instantaneous velocity tells us the rate of change at which a given object is moving along a certain path at a given instance of time, which usually tends to be infinitesimally small.

paragraphs: When formula_10, we can see that formula_11. Taking that into consideration we can conceptualize this rate of change between displacement vector and interval of time using mathematical analysis "(most notably-" "Calculus)"

paragraphs: Velocity can also be measured by comparing the motion of two objects. This is called relative velocity. The second object is called the reference frame. To find the relative velocity, subtract the velocity of the reference frame from the velocity of the first object. For example, Earth moves at 67,000 miles per hour around the Sun. Usually, we do not care about this motion. So we subtract the vector that represents Earth's motion from the total motion.


title: Virtual community

paragraphs: A virtual community is a group of people who share an interest, hobby or set of views. The people in it may come from many different places. They talk with each other using technology, such as the Internet, telephone calls, and email. The most common is the Internet.

paragraphs: Virtual communities may use any of the following to communicate:


title: World Wide Web

paragraphs: The World Wide Web ("WWW" or "The Web") is the part of the Internet that contains websites and webpages. It was invented in 1989 by Tim Berners-Lee at CERN, Geneva, Switzerland. Sir Tim Berners-Lee created a new markup language called HTML. Websites are composed of pages linked by hypertext links that are written in HTML.

paragraphs: The software to see the World Wide Web is called a web browser. One also needs a connection to the Internet.

paragraphs: Many companies nowadays offer limited website hosting allowing one to make websites that can be displayed on the World Wide Web like any other domain (www.stuff.com) site. These sites usually make money from advertisements instead of fees.


title: Wiki

paragraphs: A wiki is a type of website that lets anyone who can access the wiki create and change its pages. The word is Internet slang. The word "wiki" is short for WikiWikiWeb. "Wikiwiki" is a word from the Hawaiian language, meaning "fast" or "speed". Examples of wikis include Wikipedia, Wiktionary, Wikibook, Citizendium, and Conservapedia.

paragraphs: Every wiki can be changed, or edited, by anyone who has an account on the wiki, or by everyone in the world if the wiki allows it. Some important pages can only be changed by certain users. Wikis are central places where we all can share information, people can add new information, and then people read them. Wikis allow information from all around the world to be collected.

paragraphs: On a wiki, people can write pages by collaboration. Pages are watched closely to see whether changes are good or bad. If one person writes something wrong, another can correct it. Other users can also add something new to the page. Because of this, the page gets better when people change it. Administrators can block someone from editing if they vandalize, or for other reasons.

paragraphs: Users can also discuss things on wikis. Discussion can help people understand things better and get a chance to tell their views. In Wikipedia the talk pages are for that, but in some wikis, the article and the discussion are in the same page.

paragraphs: Wikis can be used for different things; not all wikis follow the same rules for using them. For example, the purpose of Wikipedia is to write articles for an encyclopedia. That is why in Wikipedia, people do not want general discussion that does not help in writing articles.

paragraphs: Ward Cunningham started the first wiki in March 1995. Many people liked it, and wrote there, after which they started similar websites. MediaWiki is the most used software for wikis. JSPWiki is one of many others. "Wiki" is also sometimes an abbreviation for Wikipedia.

paragraphs: Most wikis can be edited by anyone and everyone. Some wikis are even available to people without an account, so sometimes wikis will become a target for vandals to add unwelcome, disruptive or even misleading content. There are many ways to prevent this. Individual pages can be protected to allow only certain users, or only those with an account, to edit them. Administrators can also block users who make repeated vandalous edits after a minimum of a single warning. Vandalism may not be stopped totally, but regular, careful checking can limit the amount of disruptive edits you will see in a day.


title: Website

paragraphs: A website is a set of webpages that are joined together. People look at websites with a computer of some kind, sometimes including the computer inside mobile phones and televisions. The websites are kept on computers called web servers.

paragraphs: There is almost always a single homepage which has links to other pages that are part of that "site". Sometimes it has links to pages that are part of other "sites" as well. (Note that net jargon uses the word site, which also means a physical place in the real world, to mean a web URL). A home page serves as the introduction page of a website.

paragraphs: Websites can be used to advertise or sell things. They can also be used to talk to other people. A blog is a website where the location of the material is less relevant than who writes it, and which is more focused on dialogue. Very often the people who use blogs dislike the word "site" since it implies a controlled place. Sites are good for looking up information on the computer.

paragraphs: Users can access any website by using a URL. This is the website address which is shown near the top of the web browser. The homepage and the rest of the site usually have the same words at the start of the URL — for instance, pages at the Simple English Wikipedia always start "http://simple.wikipedia.org/..." but are different after that. However, if a person does not buy a domain name the website could be an IP Address which for example could be (127.0.0.1)

paragraphs: Web sites are usually shown in HTML (Hyper Text Markup Language) but are not always written or kept that way - some use WAP and others use XML.

paragraphs: Website builder software is usually a collection of software tools that allow the construction of websites without manual code editing. Several hosted website services have website builder software built-in.


title: Word

paragraphs: A word is something spoken by the mouth, that can be pronounced. In alphabetic writing, it is a collection of letters used together to communicate a meaning. These can also usually be pronounced. A logogram is also a word.

paragraphs: Some words have more than one meaning, for example 'spring' can refer to the season, the device, or a conjugation of the verb. These are homonyms. Some words have different pronunciation, for example, 'wind' (the noun) and 'wind' (the verb) are pronounced differently.

paragraphs: Some words have different spelling for example 'color' and 'colour', which are both correct. Color is used in American English and colour is used in British English. Some words can be only one letter, for example "a" and "I" in English. Besides English, other languages have their own words. When written with an alphabet, words are usually separated by a space. When written with ideograms, each word is usually a separate symbol.

paragraphs: Words can be invented. This is called neologism. For example, radar was originally an acronym but became an actual word. Two words may be joined to make a compound word.

paragraphs: A word is the smallest thing which can be said "with meaning". For example, "hello" is a word.

paragraphs: This contrasts with a morpheme, which is the smallest unit of meaning but may not stand on its own. A word may consist of a single morpheme (for example: "oh!, rock, red, quick, run, expect"), or several ("rocks, redness, quickly, running, unexpected"), whereas a morpheme may not be able to stand on its own as a word (in the words just given, these are "-s, -ness, -ly, -ing, un-, -ed").

paragraphs: The meaning of a word can be found in a dictionary.


title: Web browser

paragraphs: A web browser is a computer program application for reading pages of the World Wide Web. Since the late 1990s, most personal computers and mobile phones and other mobile devices have a browser.

paragraphs: Web browsers are used by people to find and look at web sites on the Internet. The first web browser was created in 1990. Many different web browsers are available for free. All web browsers can go to websites but each browser has good things and bad things about it. For example, some browsers focus on data security and keeping computers safe from viruses. Other browsers are made so that web pages appear on screen faster.

paragraphs: Some popular web browsers available to download:

paragraphs: A webpage is one page of a website. Every web page has a web address.

paragraphs: A web browser goes to a web page using a web address. It downloads the HTML file stored at that address. It then reads and translates the HTML file. The browser will then show the webpage on the screen as text, images and clickable links.


Web


title: Webpage

paragraphs: A webpage (or web page) is a document from the internet which can be seen with a web browser. Web pages each have a URL or address, which is how a page is found, and is different for every page. When a webpage is part of a larger group of pages managed by a company, person, or organization, it is part of a website.

paragraphs: Pages can have words, pictures, videos, and links. Links are ways to get to other web pages.

paragraphs: For example, this article is a webpage. It has the URL https://simple.wikipedia.org/wiki/Webpage, and is part of the Wikipedia website. It has words and links. The links in this page are shown in blue and can be clicked to go to other webpages.

paragraphs: Web pages are usually stored in HTML code which describes what to show on the page like words or pictures. Web pages also use two other types of code to tell the page how to work:


title: Wiktionary

paragraphs: Wiktionary is a dictionary, or a group of meanings for words, in the form of a wiki. There are many languages of Wiktionary. Wiktionary is also a thesaurus. Wiktionary is run by the Wikimedia Foundation, which also runs Wikipedia. The English Wiktionary currently has over 6.1 million pages and 3.5 million users. Much like Wikipedia, the Wiktionary is run in several different languages that can be selected from the homepage.

paragraphs: In 2006, there was a vote for the change of the logo of Wiktionary. The original logo of only words was replaced. However, there were very few people who voted in this contest. Therefore, smaller wikis used the newer logo but the English Wiktionary stayed with the same logo.

paragraphs: In 2009, there was a second contest for a newer logo "(pictured)". This was a step to make all the Wiktionaries to have the same logo on all projects. However, the English Wiktionary still did not use the new logo. The Simple English Wiktionary voted on the new logo on November 30, 2010 and the community decided the new logo to use it as their logo. However, no changes were made to the logo and the discussion was thus forgotten.


title: Microsoft Windows

paragraphs: Microsoft Windows is an operating system for computers made by the United States-based company Microsoft. Windows is used by almost 90% of desktop and laptop computers.

paragraphs: The first version of Windows, Windows 1.0, came out on November 20, 1985. The newest version, Windows 10, came out July 29, 2015. Most new personal computers come with Windows 10. However, some older or cheaper personal computers may come with Windows 8.1 or Windows 7.

paragraphs: Windows makes it easier to run programs (applications) than MS-DOS did. DOS, required typed commands to make the computer do something. DOS required correct syntax of each command. Making mistakes caused the computer to usually give an error message and do nothing.

paragraphs: Users control their Windows computer by its graphical user interface (or GUI for short). It only needs a keyboard "or" a mouse to work. In later versions, a touch screen works as well. However, using both a keyboard and a mouse makes many tasks easier. By clicking a few buttons on the screen, Windows helps keep your files safe, and easier to change and move. Versions of Windows after 2005 make it even easier for some users with disabilities because these versions have touch screens. For use of a touch screen, some mobile devices come with Windows. Tablet computers and smartphones such as Microsoft Surface and Microsoft Lumia use Windows.

paragraphs: The following programs are included with Windows:

paragraphs: Windows has several kinds of applications/programs available. Popular applications include games, word processors (to write words) or additional programs like Adobe Flash Player (to watch some videos and play many games on internet sites). Adding new applications to Windows is called "installing". Applications can be bought/purchased on a CD or DVD. Applications can also be downloaded from the Internet.  Some internet applications can be downloaded for free, and others can be bought using the internet.

paragraphs: Many users complain that Windows creates problems for them. Some users complain that Windows made their computers slower when they changed from DOS. Many people also complain about problems that make their computer less safe to use, even though Microsoft tries to fix these problems. Many computer viruses are created to infect computers running Windows since it is such a popular operating system. Windows was the most popular operating system until recently (today mobile operating systems such as Android are more popular).


title: Window

paragraphs: A window is an opening in a wall or roof of a building, in a car etc., to let air and light in. It is usually filled with a sheet of glass. There can be many different shapes and sizes, including rectangular, square, circular, or irregular shapes. Some windows include coloured glass. Windows are usually transparent so that people can see through them.

paragraphs: Before glass was used in windows, people in Asia used paper to fill the hole in the wall. The paper would let light in.

paragraphs: These are different types of windows. They are:

paragraphs: A cross-window is a window that has a mullion and a transom, that makes a cross.

paragraphs: A fixed window is a window that cannot be opened. It is made to allow light to enter. The windows in churches are usually fixed.

paragraphs: A single-hung sash window is a window that has one horizontal sash at the bottom that can move up and down.

paragraphs: A double-hung sash is a window that has two horizontal sash at the top and bottom that can move up and down.

paragraphs: A casement window is a window with a sash that has a hinge that swings in or out like a door. Casement windows are usually held open using a casement stay.

paragraphs: A skylight is a window built into a roof. This type of window allows natural daylight and moonlight to enter.

paragraphs: A roof lantern is a glass structure that has lots of different colors. It looks like a small building. It is built on a roof for day or moon light.

paragraphs: A stained glass window is a window that is made up of pieces of colored glass. The colored glass can be transparent, translucent or opaque. It usually shows people or places. Usually the glass in these windows is separated by lead rods. Stained glass windows are very common in churches.

paragraphs: Different materials are used when making a window. For the frame of the window wood, polyvinyl chloride, composite, aluminium, steel, fiberglass are used.

paragraphs: Many windows have movable window coverings such as blinds or curtains. They keep out light, give extra insulation. It also ensure privacy. Windows allow natural light to enter. But too much can have bad effects such as glare and heat gain.


title: Wine

paragraphs: Wine is an alcoholic drink. The word "wine" is usually used to talk about drinks made from the juice of grapes, although people sometimes call alcoholic drinks made from the juice of other fruits (such as plums or blackberries) "wine". This article only deals with wine made from grapes.

paragraphs: Wine is made by the fermentation of the sugar in grapes. There are two main types of wine, red wine and white wine. Red wine is made from red grapes in contact with their skins, and white wine is made from red and white grapes, but without any skin contact. Rosé wine is made by leaving red grapes in skin contact for a very short time. The colour comes only from the skin, so if you have short skin contact, the wine will not turn red but only "pink" (rose wine). Wine sometimes has bubbles in it; this wine is called sparkling wine. The most popular sparkling wines are champagne, which comes from France and spumante, from Italy.

paragraphs: People have been making wine for about 5000 years.

paragraphs: Wine is a popular drink in many countries. The countries that drink the most wine (using numbers from the year 2000) are:

paragraphs: However, if you make a list of countries where the average person drinks the most wine, the list is different:

paragraphs: Luxembourg, France, Italy, Portugal, Croatia, Switzerland, Spain, Argentina, Uruguay, and Slovenia.

paragraphs: Wine is made in many countries. The countries that make the most wine (using 2015 numbers) are:

paragraphs: Italy, France, Spain, USA, Argentina, Chile, Australia, South Africa, China and Germany.


title: Width

paragraphs: Width or breadth is the side-to-side length, measuring across the object at right angles to the height.

paragraphs: For example, the distance between the left side and right side of a chair is its width.


title: Water

paragraphs: Water () is a transparent, tasteless, odorless, and almost colorless chemical substance and covers over 70% of Earth's surface. No known life can live without it.

paragraphs: Lakes, oceans, seas, and rivers are made of water. Precipitation is water that falls from clouds in the sky. It may be rain (liquid) if it is warm, or it may be frozen if it is cold. If water gets very cold (below ), it freezes and becomes ice, the frozen variant of water. If water gets very hot (above ), it boils and becomes steam or water vapor. It is moved around in the water cycle. Water is essential for life. Some studies suggest that by 2025 more than half the people around the world will not have enough fresh water.

paragraphs: Water is a fluid. Water is the only chemical substance on Earth that exists naturally in three states. People know of over 40 anomalies about water. Unlike most other liquids such as alcohol or oil, when water freezes, it expands by about 9%. This expansion can cause pipes to break if the water inside them freezes.

paragraphs: Water is a molecule made of 2 hydrogen atoms and 1 oxygen atom. Its chemical formula is HO.

paragraphs: Like other liquids, water has a surface tension, so a little water can make drops on a surface, rather than always spreading out to wet the surface. Things having something to do with water may have "hydro" or "aqua" in their name, such as hydropower or aquarium, from the Greek and Latin names for water. It is also called the universal solvent, because it dissolves many things.

paragraphs: In small amounts, water appears to have no colour but in large amounts (such as seas or lakes), it has a very light blue color.

paragraphs: Plants and animals (including people) are mostly water inside, and must drink water to live. It gives a medium for chemical reactions to take place, and is the main part of blood. It keeps the body temperature the same by sweating from the skin. Water helps blood carry nutrients from the stomach to all parts of the body to keep the body alive. Water also helps the blood carry oxygen from the lungs to the body. Saliva, which helps animals and people digest food, is mostly water. Water helps make urine. Urine helps remove bad chemicals from the body. The human body is between 60% and 70% water, but this value differs with age; i.e. a foetus is 95% water inside.

paragraphs: Water is the main component of drinks like milk, juice, and wine. Each type of drink also has other things that add flavor or nutrients, things like sugar, fruit, and sometimes alcohol. Water that a person can drink is called "potable water" (or "drinking water"). The water in oceans is salt water, but lakes and rivers usually have unsalted water. Only about 3% of all the water on earth is fresh water. The rest is salt water.

paragraphs: Many places, including cities and deserts, don't have as much water as people want. They build aqueducts to bring water there.

paragraphs: Though people can survive a few months without food, they can only survive for a day or two without water. A few desert animals can get enough water from their food, but the others must drink.

paragraphs: Water is also used for recreational purposes, "see list of water sports".

paragraphs: Water is used as both the coolant and the neutron moderator in most nuclear reactors. This may be ordinary water (called light water in the nuclear industry) or heavy water.

paragraphs: Water is also used for washing a lot of objects. Goods, services and people are transported to other countries in watercrafts on bodies of water.

paragraphs: Water is used in chemical reactions as a solvent or reactant. Water is also used in fire fighting. Water is also used for cooking.

paragraphs: The dihydrogen monoxide parody involves calling water by the unfamiliar chemical name "dihydrogen monoxide" (DHMO) and listing some of its harmful effects in an alarming way. Some examples include talking about how "it causes burning, suffocation and corrosion," when it's actually just talking about hot water, drowning and rust. Sometimes the parody calls for it to be banned and/or labelled as dangerous.

paragraphs: The prank works because it takes advantage of people's misunderstanding. Calling water by an unfamiliar name and making it sound like a harmful chemical can make people think it's dangerous, if they don't know that you're just talking about water.

paragraphs: "Dihydrogen monoxide" is an alternative chemical name for water, but nobody uses it. The word "dihydrogen" means two hydrogens, and "monoxide" means one oxygen. Water's chemical formula has two hydrogens and one oxygen.

paragraphs: The parody gained most of its popularity in the 1990s, when a 14-year-old named Nathan Zohner collected anti-DHMO petitions for a science project about gullibility. Zohner fooled a lot of people, which has led to his project being used in lessons about critical thinking and the scientific method.

paragraphs: The website DHMO.org is a joke website which lists the harmful effects of water (DHMO), answers questions, and calls for it to be banned among other things.

paragraphs: A BBC short item explains that every molecule on Earth has existed for billions of years, and all of them came from elsewhere. Water is alien because it arrived on asteroids and comets. It is the second most common molecule in the universe. Why is it not a gas? It is made of two very light elements. Ice floating on water is also an oddity. Also, hot water freezes faster than cold, and no-one knows why this is. Molecules of water can move up against the force of gravity (that's due to surface adhesion).

paragraphs: Much of the universe's water is produced as a byproduct of star formation.

paragraphs: On 22 July 2011, a report described the discovery of a gigantic cloud of water vapor containing "140 trillion times more water than all of Earth's oceans combined" around a quasar located 12 billion light years from Earth. According to the researchers, the "discovery shows that water has been prevalent in the universe for nearly its entire existence".

paragraphs: Water has been detected in interstellar clouds in our galaxy, the Milky Way. Water probably exists in abundance in other galaxies, too. Its components, hydrogen and oxygen, are among the most abundant elements in the universe. Most other planetary systems are likely to have similar ingredients.

paragraphs: Liquid water is found on Earth. It covers about 71% of the surface of the Earth. Liquid water is sometimes found in small amounts on Mars. Scientists believe that liquid water is in Enceladus, Titan, Europa and Ganymede.


title: Want

paragraphs: A want is a wish or a desire for something. If a person would like to have something, but can choose not to have it, that thing is wanted or can be called a want. To want is not the same as to need, which is when someone "must" have something.

paragraphs: People often talk about needing a thing, when they really just want it. Wants can be for the same things as needs. For example, a person can "need" to eat food and can "want" to eat cake. If there is no cake then he or she may have to eat something else, perhaps bread. The need is no longer so important (the person is no longer hungry) although the want may still be there. If there is cake, then the person's needs and wants can both be met.

paragraphs: In economics, a want is about goods or services. Choice is how to satisfy a want, when there are different ways to do this.

paragraphs: Want can also be the idea of what it means to be poor, hungry or with no money. Charles Dickens wrote a famous book called "A Christmas Carol" in which there are two children, named Want and Ignorance.


title: War

paragraphs: War is a situation or a period of fighting between countries or groups of people. A war generally involves the use of weapons, a military organization and soldiers. War is a situation in which a nation enforces its rights by using force. Not every armed conflict is a war. A fight between individuals, between gangs, drug cartels, etc. is not considered a war. However, most wars are called armed conflicts. International humanitarian law is a set of rules that tries to limit the effects of wars. International Humanitarian Law recognizes two kinds of wars. These are:

paragraphs: Karl von Clausewitz wrote in his classic book, "On War", that "war is a mere continuation of policy with other means.” Clausewitz viewed war as a political instrument. His book about military philosophy remains the most influential work on the history and strategy of war. An earlier authority on war was Sun Tzu. In his book "The Art of War", Sun Tzu saw war as a necessary evil. It was something people do.

paragraphs: Wars have been fought to control natural resources, for religious or cultural reasons and over political balances of power. They have been fought over legitimacy (correctness) of particular laws. They have been fought to settle arguments about land or money, and many other issues. The reasons behind any war are often very complex. While a war can start for just about any reason, there is usually more than one cause. War is also a terrible coincidence to be through

paragraphs: From the earliest times, individual states or political factions have used war to gain sovereignty over regions. In one of the earliest civilizations in history, Mesopotamia, they were in a near constant state of war. Ancient Egypt during its Early Dynastic Period came about by war when Lower and Upper Egypt were joined together as one country, about 3100 BC. The Zhou Dynasty ruled Ancient China came to power in 1046 through war. Scipio Africanus (236-183 BCE) defeated Carthage leading Ancient Rome to begin a conquest of the known world. Philip II of Macedon (382-336 BCE) united a group of city-states to become Ancient Greece.

paragraphs: Sometimes, people don't see a difference between fighting between countries or people, and the formal declaration of a state of war. Those who do see this difference usually only use the word "war" for the fighting where the countries' governments have officially declared war on each other. Smaller armed conflicts are often called riots, rebellions, coups, etc.

paragraphs: One country may send forces to another country for a variety of reasons. Sometimes it is to help keep order or prevent killings of innocents or other crimes against humanity. It may be to protect a friendly government against an uprising. Here it may be called a police action or humanitarian intervention instead of a war. Some people think it's still a war.

paragraphs: Another kind of war existed from 1947 until 1991 called the Cold War. This started when diplomatic relations between the United States and the Soviet Union broke down. Both countries had nuclear weapons and both stood ready to use them against the other. But there was no actual war between the two. It ended with the fall of the Soviet Union in 1991. The cold war was also called a containment where the United States tried to prevent the spread of communism to other countries. During the cold war, the major powers did not fight themselves, but often backed third parties in what was called a proxy war. The Vietnam War is often given as an example of a proxy war. But proxy wars happened long before the cold war and are still happening.

paragraphs: A war between peoples and groups in the same country is known as a civil war. It is generally agreed there are two things that make a war a civil war. It must be a struggle between groups in the same country or state over political control or to force a major change in the government's policy. The second criterion is that more than 1000 people have to have been killed, with a minimum of 100 from each side. The American Civil War is an example of a civil war. While the figures are mere estimates, the total casualties are thought to be about 750,000.

paragraphs: Only in the last 150 years or so, have states agreed on international laws to limit warfare. This has been mainly for humanitarian reasons. The Geneva conventions and the Hague Conventions are two examples of agreements that establish laws governing wars. Collectively, these are usually called International humanitarian law (IHL). Because these are established laws, they restrict those engaged in armed conflicts to follow the IHL. Also, a country must not only respect the law but they also need to make sure other countries respect it as well. They cannot turn a blind eye (meaning pretend they do not see a thing) to countries who are not following IHC. The first of these was the Geneva Convention in 1864. It became international law with the signatures of 100 countries.

paragraphs: The statistical analysis of war was started by Lewis Fry Richardson following World War I. More recent databases of wars have been assembled by the Correlates of War Project and Peter Brecke.


title: Yiddish

paragraphs: Yiddish is a language used by some Jews. At first, it was a dialect of German that Jews began to use in Europe about 1000 years ago. It was and still is used in the United States, especially in New York, and other countries that Jews have moved to.

paragraphs: Most of its words come from German, and Yiddish also has many words from Hebrew and Slavic languages, especially Polish, and some words from French, Hungarian and Latin. Yiddish usually uses the Hebrew script.

paragraphs: In the whole world, Yiddish is spoken by about 3 million people, mainly Hasidic Jews.

paragraphs: In the Netherlands and Sweden, Yiddish is protected by the European Charter for Regional or Minority Languages.


title: Year

paragraphs: One year is about 365 days long (except in a leap year). It is the time it takes the Earth to go completely around (orbit) the sun once. A year is actually 365.2422 days long, but a calendar has 365 days, except in a leap year.

paragraphs: The year starts on January 1 and ends on December 31 in the Gregorian calendar, but a fiscal year or a school year can start on a different day of the year.

paragraphs: There are several ways used to measure the length of a year.

paragraphs: Solar and lunar years are used by different calendars for daily life. The other measurements are used by astronomers.


title: You

paragraphs: You is a second-person English pronoun. The word can be singular or plural. It is what a person says when he or she is addressing another person in second person. Sometimes, just using the English letter "u" is acceptable, and "ur" for the words "you're" and "your". This is very informal, and is mostly used in texting.


title: Chinese language

paragraphs: The Chinese language is the group of languages used by Chinese people in China and elsewhere. It forms part of a language family called the Sino-Tibetan family of languages.

paragraphs: Chinese includes many regional language varieties, the main ones being Mandarin, Wu, Yue and Min. These are not mutually intelligible and many of the regional varieties are themselves a number of non-mutually-intelligible subvarieties. As a result, many linguists refer to these varieties as separate languages.

paragraphs: 'Chinese' can refer to the written or the spoken languages. Although there are many spoken Chinese languages, they use the same writing system. Differences in speaking are reflected in differences in writing. Official China adopts a similar policy to the one in the Soviet Union, using one official language so people can understand each other. The Standard Chinese language is referred to as Mandarin in English, ""Pǔtōnghuà"" or "common to everybody speech" in mainland China and ""Guóyǔ"" or "language of the whole country" in Taiwan. All official documents are written in Mandarin and Mandarin is taught all over China. It is also a standard for language teaching in some other countries.

paragraphs: Chinese is used by the Han people in China and other ethnic groups in China who are declared Chinese by the Chinese government. Chinese is almost always written in Chinese characters. They are symbols that have meaning, called logograms. They also give "some" indication of pronunciation, but the same character can get very different pronunciations among the different kinds of Chinese. Since Chinese characters have been around for at least 3500 years, people in places far from each other say them differently, just as "1, 2, 3" can be read differently in different languages.

paragraphs: Chinese people needed to write down pronunciations in dictionaries. Chinese does not have an alphabet, so how to write down sounds was a big problem in the beginning. Nowadays the Mandarin language uses Hanyu Pinyin to represent the sounds in Roman letters.

paragraphs: All the Chinese languages (or dialects) use tones. This means that they use high and low pitches to help make differences in meaning clear.

paragraphs: The Chinese language is like a big tree. The base of the tree started thousands of years ago. It now has several main limbs. Some people call "just a branch" what other people call a main limb, so you can say there are six or seven main limbs. Each of these main limbs splits off into branches about the way there are branches of English spoken in Great Britain, the United States, Australia, India, and so forth. Just as the Romance languages all come from the area around Rome and are based on Latin, the Chinese languages all have some common source, so they keep many common things among them.

paragraphs: Here are the main seven main groups of languages/dialects of Chinese by size:

paragraphs: In 1956, the government of the People's Republic of China made public a set of simplified Chinese characters to make learning, reading and writing the Chinese language easier. In Mainland China and Singapore, people use these simpler characters. In Hong Kong, Taiwan and other places where they speak Chinese, people still use the more traditional characters. The Korean language also uses Chinese characters to represent certain words. The Japanese language uses them even more often. These characters are known in Korean as Hanja and in Japanese as Kanji.

paragraphs: A Chinese person with a good education today knows 6,000-7,000 characters. About 3,000 Chinese characters are needed to read a Mainland newspaper. However, people who have learned only the 400 most frequently used characters can read a newspaper—but they will have to guess some less-used words.

paragraphs: Here are some samples of some words and sentences in Mandarin Chinese. Simplified Characters are on the left, and Traditional characters are on the right. The pronunciation is given in the pinyin system, which may not always be as simple as it looks for those who have not studied it.

paragraphs: The Traditional Characters are now used in Hong Kong and Taiwan. Chinese from Mainland China uses the Simplified Characters, but may recognize Traditional Characters.

paragraphs: Before 1956, Chinese was written using only Traditional Characters. At that time most Chinese people could not read or write at all. The government of the People's Republic of China thought that the Traditional characters were very hard to understand. They also thought that if they made the characters simpler more people could learn how to read and write. Today, many people in China can read and write with the new Simplified Characters.


title: Zero

paragraphs: Zero (0) is a special number. If there are zero things, then there is nothing at all. For example, if a person has zero hats, that means they do not have any hats.

paragraphs: The symbol for the number zero is "0". It is the additive identity of common numbers. This means that if a number is added to 0, then that number would remain unchanged.

paragraphs: The idea of zero was first thought about in Babylon, India and in Central America at different times. Some places and countries did not know about zero, which may have made it harder for those people to do mathematics. For example, the year after 1 BC is AD 1 (there is no year zero). In India, zero was theorized in the seventh century by the mathematician Brahmagupta.

paragraphs: Over hundreds of years, the idea of zero was passed from country to country, from India and Babylon to other places, like Greece, Persia and the Arab world. The Europeans learned about zero from the Arabs, and stopped using Roman math. This is why numbers are called "Arabic numerals".

paragraphs: Zero is almost never used as a place number (ordinal number). This means that it is not used like 1, 2, or 3 to indicate the order, or place, of something, like 1st, 2nd, or 3rd. An exception to this is seen in many programming languages.

paragraphs: Any number divided by itself equals one, except if that number is zero. In symbols:

paragraphs: In time, zero means "now". For example, when a person is counting down the time to the start of something, such as a foot race or when a rocket takes off, the count is: "three, two, one, zero (or "go")". Zero is the exact time of the start of the race or when the rocket takes off into the sky.

paragraphs: 0 is the integer that precedes the positive 1, and follows −1. In most (if not all) numerical systems, 0 was identified before the idea of 'negative integers' was accepted. It means "courageous one" in hieroglyphics.

paragraphs: Zero is a number which means an amount of null size; that is, if the number of brothers is zero, that means the same thing as having no brothers, and if something has a weight of zero, it has no weight. If the difference between the numbers of pieces in two piles is zero, it means the two piles have an equal number of pieces. Before counting starts, the result can be assumed to be zero; that is the number of items counted before one counts the first item, and counting the first item brings the result to one. And if there are no items to be counted, zero remains the final result.

paragraphs: While mathematicians all accept zero as a number, some non-mathematicians would say that zero is not a number, arguing that one cannot have zero of something. Others say that if one has a bank balance of zero, one has a specific quantity of money in that account, namely none. It is that latter view which is accepted by mathematicians and most others.

paragraphs: Normally speaking, there was no year zero between 1 BC and 1 AD. More specifically, almost all historians leave out the year zero from the proleptic Gregorian and Julian calendars (that is, from the normal calendar used in English-speaking countries), but astronomers include it in these same calendars. However, the phrase Year Zero may be used to describe any event considered so important, that someone might want to start counting years all over again from zero.

paragraphs: The modern numeral 0 is normally written as a circle or (rounded) rectangle. In old-style fonts with text figures, 0 is usually the same height as a lowercase x.

paragraphs: On the seven-segment displays of calculators, watches, etc., 0 is usually written with six line segments, though on some historical calculator models, it was written with four line segments. The four-segment 0 is not common.

paragraphs: The "number" zero (as in the "zero brothers" example above) is not the same as the "numeral" or "digit" zero, used in numeral systems using positional notation. Successive positions of digits have higher values, so the digit zero is used to skip a position and give appropriate value to the preceding and following digits. A zero digit is not always necessary in a different positional number system. Something called bijective numeration is a possible example of a system without zeroes.

paragraphs: 0 (zero) is also used as a numerical digit used to represent that number in numerals. It is used to hold the place of that digit, because correct placing of digits affects a numeral's value.

paragraphs: The number 0 and the letter O are both round, though of different widths. The difference is important on a computer. For one thing, a computer will not do arithmetic with the letter O, because it does not know that it should have been a zero.

paragraphs: The oval-shaped zero and circular letter O came into use together on modern character displays. The zero with a dot in the centre seems to have begun as a choice on IBM 3270 controllers (this has the problem that it looks like the Greek letter theta). The slashed zero, looking like the letter O with a diagonal line drawn inside it, is used in old-style ASCII graphic sets that came from the default typewheel on the well-known ASR-33 Teletype. This format causes problems because it looks like the symbol formula_1, representing the empty set, as well as for certain Scandinavian languages which use Ø as a letter.

paragraphs: The rule which has the letter O with a slash and the zero without was used at IBM and a few other early mainframe makers; this is even more of a problem for Scandinavians, because it looks like two of their letters at the same time. Some Burroughs/Unisys computers display a zero with a backwards slash. And yet another convention common on early line printers left zero without any extra dots or slashes but added a tail or hook to the letter O so that it resembled an inverted Q or cursive capital letter O.

paragraphs: The letters used on some European number plates for cars make the two symbols look different. This is done by making the zero rather egg-shaped and the O more circular, but most of all by cutting open the zero on the upper right side, so the circle is not closed any more (as in ). The style of letters chosen is called "" (abbr.: "FE Schrift"), meaning "script which is harder to falsify". But those used in the United Kingdom do not make the letter o and the number 0 look different from each other, because there can never be any mistake if the letters are correctly spaced.

paragraphs: In paper writing you do not have to make the 0 (zero) and O (letter O) look different at all. Or you may add a slash across the zero in order to show the difference.

paragraphs: Functions are explained in the Function (mathematics) article. If the function "f"("x") = 0, then "x" is called a zero (or root) of the function "f". For example, if the function "f"("x") is "x" − 1, then the zeroes of the function are +1 and −1, because "f"(+1) = (+1) − 1 = 0, and "f"(−1) = (−1) − 1 = 0.

paragraphs: Zeroes of a function are used because they are another way to talk about solving an equation, which is a main goal in algebra. If we want to solve an equation like "x" = 1, then we can subtract the right-hand side of the equation from both sides, in this case 1. Whatever we get on the left-hand side, in this case "x" − 1, can be called a function "f"(x). The right-hand side has to be zero, because we subtracted it from itself. So "f"(x) = 0. Finding the zeroes of this function is the same as solving this equation. In the paragraph before, the zeroes of this function are +1 and −1, so they are the solutions of this equation. We got this equation by subtracting the same thing from both sides, so we also have solutions to the equation we started with, in this case "x" = 1. More generally, if we could find zeroes of functions, we could solve any equation.


title: Zoology

paragraphs: Zoology is the science of studying animal life. It is part of biology. The word is pronounced "Zō-ölogy", not "Zoo-ology". Animal life is classified into groups called phyla, of which there are at least thirty.

paragraphs: Zoologists are scientists who study animals. They may work in laboratories, or do field research. The methods are many and various. At the heart, they cover the structure, function, ecology and evolution of animals. The structure is investigated by dissection, and microscopic examination. The function is investigated by observation and experiment. Palaeontology supplies information about extinct animals. Zoologists may be employed by universities, museums, or by zoos.


title: Zinc

paragraphs: Zinc, sometimes called spelter, is a chemical element. It is a transition metal, a group of metals. It is sometimes considered a post-transition metal. Its symbol on the periodic table is "Zn". Zinc is the 30th element on the periodic table, and has an atomic number of 30. Zinc has a mass number of 65.38. It contains 30 protons and 30 electrons. In total, 29 isotopes of zinc are known, and five of these occur in nature. Some isotopes are radioactive. Their half-lives are between 40 milliseconds for Zn and 5x10 years for Zn.

paragraphs: Zinc is a metal that is mostly used for galvanizing and batteries. It is the fourth most common metal.

paragraphs: Zinc is a shiny bluish grey metal. When it has just been cut, zinc has a whitish-grey color. If it is exposed to air, it will not stay shiny for long. Its melting point is at (), boiling point is (), cooling point is at , and freezing point is at . This temperature is lower than most transition metals but higher than tin or lead. It can be melted on a cooking stove. It boils at a low temperature for a metal. It is not magnetic. When heated a little, it becomes very flexible. If it is heated more, it becomes very brittle. It forms alloys easily with other metals.

paragraphs: Zinc is a reactive metal. It is about as reactive as aluminium and more reactive than most of the more common metals, such as iron, copper, nickel, and chrome. It is less reactive than magnesium. Zinc can react with acids, bases, and nonmetals. It does not rust in air, though. A coating of zinc oxide and zinc carbonate forms on the surface of the zinc when it is in air. This coating stops corrosion. Acids can dissolve this coating and react with the zinc metal. This reaction of zinc with an acid makes a zinc(II) salt such as zinc chloride and hydrogen gas. This is a very common chemical reaction. The reaction below is the reaction with hydrochloric acid.

paragraphs: Zinc can burn when powdered or in small pieces to make zinc oxide, a white powder. The flame is bright blue-green.

paragraphs: Zinc oxide can dissolve in strong bases. This reaction happens in some batteries that have zinc in them.

paragraphs: Zinc is a chalcophile. This means that it would rather react with sulfur and elements below it on the periodic table than oxygen. That is why zinc sulfide is the most common zinc ore, not zinc oxide.

paragraphs: Zinc can make chemical compounds with other elements. These chemical compounds are only in one oxidation state: +2. A +1 compound has been found but it is hard to make. There are no other oxidation states other than +1 or +2. Most of these compounds have no color. If they have a color, it is not the zinc that is making the color.

paragraphs: Zinc chloride is one of the most common zinc compounds. They are quite unreactive. They are a little acidic when dissolved in water. They make a green flame when heated in a fire.

paragraphs: Five isotopes of zinc are found in nature. Zn is the most common isotope, with 48.63% of naturally occurring Zinc. This isotope has a half-life of 4.3x10 years. This is so long, that its radioactivity can be ignored. Similarly, (0.6%), with a half life of 1.3x10 years is usually considered to not be radioactive. The other isotopes found in nature are (28%), (4%) and (19%).

paragraphs: Zinc is not found as a metal in the earth's crust. Zinc is only found as zinc compounds. Sphalerite, a mineral that is made of zinc sulfide, is a main ore of zinc. Very little zinc is in the ocean. Zinc ore is normally found with copper and lead ores.

paragraphs: There are some other zinc ores, such as smithsonite (zinc carbonate) and a zinc silicate mineral. They are less common.

paragraphs: The zinc sulfide is concentrated by flotation. There is a detergent that collects the zinc sulfide. The impurities sink to the bottom and are removed. Then the zinc sulfide is heated in air to make zinc oxide and sulfur dioxide.

paragraphs: The sulfur dioxide is oxidized to sulfur trioxide.

paragraphs: The sulfur trioxide reacts with the zinc oxide to make zinc sulfate. This makes a soluble form of zinc which can be processed more.

paragraphs: The zinc sulfate is purified and electrolyzed. This electrolysis makes oxygen, zinc, and sulfuric acid. This makes a pure zinc that is known as "SHG" or special high grade.

paragraphs: The sulfuric acid is reused in place of the sulfur trioxide to leach more zinc oxide.

paragraphs: Zinc oxide can also be reduced by carbon to zinc metal and carbon dioxide at high temperatures. This is a blast furnace process similar to how iron is made.

paragraphs: This form of zinc is cheaper but is not pure.

paragraphs: Zinc is the fourth most common metal in the world. About 10 million tons are made every year.

paragraphs: Zinc is used in electrical batteries. The alkaline cell and the Leclanche cell are the ones that use zinc the most. It becomes oxidized and provides electrons for the battery to run.

paragraphs: About 59% of zinc is used for corrosion prevention, which includes galvanizing. 47% of the world's zinc is used for galvanizing. This is used to protect another metal, usually iron, from rusting. The zinc coating corrodes instead of the iron. The zinc coating can be placed on the metal in two ways. The metal can be dipped into a pot of melted zinc. The zinc can also be electroplated on to the metal. Dipping lasts longer but has a patchy surface that some do not think looks nice. It is also used in motorboats and pipelines to slow rusting. The motor of a motorboat often has a "bullet" of zinc, that will corrode easily, but will help other metal parts of the motor to stay rust free.

paragraphs: Zinc is used in alloys. Brass is an alloy of copper and zinc. Brass is the most common zinc alloy. Zinc can form alloys with many other metals. Zinc aluminium is an alloy of zinc and aluminium, which makes good bearings. Commercial bronze has zinc in it. Sometimes cadmium telluride is reacted with zinc to make cadmium zinc telluride, a semiconductor. Nickel silver is another zinc alloy.

paragraphs: Zinc can be used in the pipes of a pipe organ. An alloy of tin and lead was used in the past. Zinc is used in the US penny, where it only has a thin layer of copper. The core is zinc. Older pennies were made completely out of bronze.

paragraphs: A mixture of powdered zinc and sulfur can be used to propel a model rocket. This reaction makes zinc sulfide, heat, light, and gases. Zinc sheet metal is used to make zinc bars.

paragraphs: About 1/4 of zinc is used to make zinc compounds. Zinc oxide can be used for sunscreen or paint pigment. Zinc oxide also is a semiconductor. Zinc chloride is used to preserve wood so it does not rot. Some fungicides have zinc in them. Zinc sulfate is used in dyes and pigments. Zinc sulfide is used in fluorescent bulbs to convert the ultraviolet light to visible light.

paragraphs: Humans need a little bit of zinc to help their body run well. If they do not get enough zinc in their food, they can get a mineral deficiency. Almost two billion people have a zinc deficiency. Zinc deficiency makes one more easily get infections. Some people say that when we get colds, we should take more zinc. Others say that zinc does not make a difference. There are medicines that one can use when they have a cold. People add tiny amounts of zinc compounds to vitamin pills and cereals to make sure that they get enough zinc. Most single-tablet vitamins have zinc in them. Zinc is found in at least 100 enzymes. It is the second most common transition metal other than iron. Zinc also is used by the brain. The human body contains 2 to 4 grams of zinc. A zinc enzyme helps remove carbon dioxide from blood. Wheat has much zinc in it.

paragraphs: Large amounts of zinc metal are toxic. It can dissolve in stomach acid. When too much zinc is eaten, copper and iron levels go down in the body. Zinc compounds can be corrosive in the stomach. Zinc compounds put in the nose can ruin the sense of smell.

paragraphs: Zinc ions are very toxic to fish and many things that live in water.


title: Zebra

paragraphs: Zebras are mammals of the family "Equidae". Zebras are African horses. They are in the same genus as the common horse, "Equus caballus", and donkeys. Zebras are known for having many black and white stripes. There are three main species of zebra, Grevy's Zebra, the Plains Zebra, and the Mountain Zebra.

paragraphs: All zebras have very short fur because they live in hot areas. Their fur has black and white stripes. The main part of the body has mostly vertical stripes, and the legs have horizontal stripes. They also have a dark line directly down their spine. Each of the different zebra species has different type of stripes. Each zebra has a unique pattern.

paragraphs: Despite many attempts, we do not really know what the advantage is of having those characteristic stripes. There are different species and sub-species of zebra, and they all have stripes so, think scientists, it must be important.

paragraphs: Zebras are social animals that spend time in herds, they graze together and sometimes even groom each other. They can have babies (foals) when they are about five years old and can have one every year. Zebras mainly eat grass, but they also eat fruit, leaves and some vegetables. They always live near water and are an endangered species.

paragraphs: Zebras live in Africa, south of the Sahara desert.


title: Zoo

paragraphs: A zoological garden, zoological park, or zoo is a place where many different species types of animals are kept so people can see and watch them.

paragraphs: Modern zoos try not only to be for people's entertainment, but for education, research, and the conservation and protection of animals. Many zoos are centers where rare animals are preserved when they are in danger of dying out. These modern zoos also want to give the animals a natural life, so that they are healthy and behave normal. This is done for the animals, but also that people can see the animals as if they were in nature, and not in a zoo.

paragraphs: Zoos cost money. They educate the public on the biological diversity that makes up the world. They help people and wildlife successfully coexist. They pursue continuing research and education for people. They preserve crucial natural resources. They work to ensure zoos can provide the most natural environment possible for wildlife in its care. Without enough money they cannot do these things.

paragraphs: Many zoos are not like the modern type of zoo. There the animals are held in bad conditions. They are kept in small cages, and they are bored and get sick.

paragraphs: There are different types of zoo all over the world. They are:

paragraphs: A safari park is a type of zoo where visitors can drive their own vehicles or ride in vehicles given by the park to see the animals. Sometimes, visitors can feed the animals through the car windows. The first safari park was Whipsnade Park in Bedfordshire, England. It was opened by the Zoological Society of London in 1931.

paragraphs: A public aquarium is a type of zoo which has lots of aquatic animals and plants for people to see. Most public aquariums have very large tanks. They may also have smaller tanks. The first public aquariums were made in the mid-19th century.

paragraphs: A petting zoo is a type of zoo that has domestic animals and some wild animals that are very calm so that the visitors can touch and feed them. Most petting zoos usually have very calm herbivorous domesticated animals, such as: sheep, goats, pigs, rabbits or ponies, to feed and touch them safely. Few petting zoos have wild animals (such as pythons or baby big cats) touch. These are rare and usually found outside Western countries.

paragraphs: An animal theme park is a combination of a theme park and a zoo. It mainly built for entertainment, amusement, and commercial reasons. Many animal theme parks combine theme park elements, like entertainment and amusement rides, with zoo elements such as live animals kept inside cages so that visitors can see them.


title: Copyright

paragraphs: With copyright, a work can only be copied if the owner gives permission. If someone copies a work without permission, the owner can say they infringed their copyright. When this happens, the owner may sue for the amount that should have been paid. Most cases are handled by civil law. In more serious cases, a person who copies a work that is protected under copyright could be arrested, fined or even go to prison. Commonly, the copy-right law will protect the authors and their heirs from 50 to 100 years since the first day of the authors' deaths.

paragraphs: In many countries, the governments tried to modify copyright law to meet international standards. However, there are still some differences, according to the law culture each country. In some countries, someone violating copyright law will be sued only to the civil law courts but other countries they can also be charged by criminal courts.

paragraphs: Copyright was originally made in the 18th century for books. Before printing presses were made, books could only be copied by hand, which would take time. But when printing presses were made, books could be copied faster and easier. Because of this, some books were copied by people who did not own the book themselves. So lawmakers gave only owners the right to copy. National laws were somewhat standardized by international treaties.

paragraphs: Because technology got better over time, copyright began to cover other types of media such as pictures, sound, and film. Commonly, copyright violation warning would be shown at the beginning of the media to warn audiences against violating copyright law.

paragraphs: In most countries, authors automatically own the copyright to any work they make or create, as long as they do not give the copyright to someone else.

paragraphs: In most countries, there is no need to register the copyright, and some countries do not even have procedures to register copyrights. But, where registration is available, many authors register anyway, especially for works that are sold for money. That is because registration helps to prove that the copyright of a work belongs to a certain author.

paragraphs: If an author gets paid to make a work for someone else, the person who pays for making the work (for example, the author's employer) will often get to own the copyright instead of the author themselves. For example, if a person working for a company, Microsoft creates a new computer software program at work, the Microsoft company would own the copyright. It is very common that the company will instead register the copyright to avoid their employees from claiming their works.

paragraphs: Copyright laws usually protect owners of copyright beyond their lifetime. In some countries, such as Canada and New Zealand, works are protected for 50 years after the last living author dies. In other countries, like the United States and the European Union, the protection lasts for 70 years after death. When the period of copyright protection has ended, the written document, musical composition, book, picture, or other creative work is in the public domain. This means that no one owns the copyright and everyone is free to copy, use and change them without having to ask for permission or pay the owner.

paragraphs: There is an exception to the rules of copyright, called fair use. This means that people can copy a very small amount of a work to use in reviews or in research reports.

paragraphs: An example of fair use is when newspaper writers quote several sentences from a copyright-protected document to tell the story. Another example of "fair use" is when a university professor quotes several sentences from a copyright-protected book in a review of the book, or in a research report.

paragraphs: Different countries have different copyright laws. Most of the differences are about:

paragraphs: Because of these differences, a certain piece of work may be under copyright in one country, and in the public domain in another.

paragraphs: Some people argue that copyright laws make it easier for people to make new works and think of new ideas. After all, if authors get to make money for the time, effort and money they put in, then they will want to make more works later, and make more money.

paragraphs: But others believe that copyright laws make it harder to be creative. Without copyright, other people could reuse existing work, and copyright law often stops that.

paragraphs: If an author wants to sell a work, it's often easiest to give the copyright to a publisher. The publisher will do all the selling, and in return for that service, will keep part of the money. But the publisher has many different things to sell, and they may not want to sell the work the author made. Authors often find it very hard to find a publisher willing to sell their work.

paragraphs: But without a publisher, it can be even harder for an author to sell his or her work. In many markets, a few big publishers own the copyrights to almost everything available, and stores will not want to sell works published by small authors themselves. Many people say copyright law helps big publishers stay in control, and keeps smaller authors out of the market. (tragedy of the anticommons).

paragraphs: As a solution to these problems, groups of authors have come up with the idea of open content. With open content, authors give everyone permission to copy, change and give away or sell their works, as long as they follow certain rules. These rules are explained in an open content license. Some possible open content rules are:

paragraphs: The term for Open Content is sometimes called Copyleft.


title: Republic of China

paragraphs: The Republic of China (), also known as Republic of China (Taiwan), is a democratic island country in East Asia. It is often called Taiwan. The People's Republic of China (PRC) is to the northwest; Japan is to the northeast; the Philippines is to the south. The Chinese Nationalists lost the Chinese Civil War to the Communists in 1949 and moved the government of the Republic of China from Nanjing to Taipei. It still claims the ownership of all of China including Mainland China.

paragraphs: The territory the Republic of China (ROC) controls is known by most people as the island of Taiwan. Most places on Taiwan Island are called "Taiwan Province" by the government of the Republic of China for official business, except the two largest cities of Taipei and Kaohsiung. West of Taiwan Island, there are three small groups of islands that also belong to ROC. They are:

paragraphs: The ROC used to govern Mainland China too. Now Mainland China is governed by the Communist People's Republic of China; see History and Political problems of China. However, ROC still declares Mainland China as its territory officially. The Republic of China also used to govern Mongolia.

paragraphs: There are administrative divisions in different levels and types.

paragraphs: 157 Districts (區 qū ㄑㄩ), 17 Country-controlled cities (縣轄市 xiànxiáshì ㄒㄧㄢˋㄒㄧㄚˊㄕˋ), 41 Urban Townships (鎮 zhèn ㄓㄣˋ), and 153 Rural Townships (鄉 xiāng ㄒㄧㄤ) stand the 3rd level. Districts stand under either Special municipalities or Provincial cities; Country-controlled cities, Urban Townships, and Rural Townships stand under Counties.

paragraphs: Villages (里 lǐ ㄌㄧˇ or 村 cūn ㄘㄨㄣ) stand the 4th level, and Neighborhoods (鄰 lín ㄌㄧㄣˊ) stand the 5th level.

paragraphs: The Nationalists, led by Dr. Sun Yat-sen, got rid of the Qing Dynasty ruled by the Manchus, then they established the ROC and ended Imperial Dynastic Rule in late-1911. The ROC at that time had Mainland China and all of what is now called Mongolia.

paragraphs: After the Japanese were defeated by the Allies during World War II, Taiwan was controlled by the ROC.

paragraphs: In 1949, the Chinese Communists fought a war against the Nationalists and won. They established the People's Republic of China. The Nationalists left mainland China and arrived in Taiwan.

paragraphs: After the ROC created a base on Taiwan, it hoped one day to capture the Mainland. But Chinese Communists grew stronger, so the Nationalists never did go back. The Communists say they replaced the ROC as the only government of China and also calls Taiwan their own.

paragraphs: There are those people in Taiwan who want to never be a part of the People's Republic of China. They believe in complete Taiwan independence and want to rename the ROC (Taiwan) to "Republic of Taiwan" so Taiwan can no longer have any ancestral connection to China or Chinese culture. Some other people wish to unite with the People's Republic of China; they want Chinese reunification. Some still want to attack the PRC and reunify China under the Republic of China. Most others want the "status quo", which means keeping everything the way it is now.

paragraphs: Most Taiwanese people speak the Standard Chinese language known as Mandarin, and others speak local dialects such as Min Nan (Taiwanese) or Hakka. The Cantonese language, spoken in parts of southern China (for example, the province of Guangdong, Hong Kong and Macau), is not spoken in Taiwan. A small percentage of Aboriginal Taiwanese speak aboriginal languages, but the rest of the Chinese people have treated them badly, and many of these people, and their languages, struggle to survive. Some older Taiwanese people who went to school while the country was under Japanese rule can speak Japanese.

paragraphs: After the Nationalist government fled the Mainland in 1948-49, they brought their language, Mandarin, with them, and made Mandarin the only official language. Then everyone in the ROC had to learn Mandarin. But, unlike the people in Mainland China, the Taiwanese never changed to simplified Chinese characters and so they have always used traditional Chinese characters. In the past, students were not allowed to speak their mother tongue in school and were expected to speak only Mandarin. Taiwanese, Hakka, and native languages were considered bad until the early 1990s, when education in these languages began to be taught in some school systems. They were promoted, but by this time, many young people could speak only Mandarin.


Simple English


title: Prison

paragraphs: A prison or jail is a building where people are forced to live if their freedom has been taken away. The main use for prisons is as a punishment for breaking the law. Those who break the law and are convicted (found guilty) in court can receive a prison sentence, which is an order to spend an amount of time in prison. Prisons are usually run by the government.

paragraphs: There are other reasons why someone might be held in prison. Sometimes, people can be held in prison before their trial (known as pre-trial detention or remand). In times of war, captured soldiers may become prisoners of war and civilians (non-soldiers) may be placed in an internment camp. In some countries, prisons are also used for political prisoners (people who disagree with the country's leader or government).

paragraphs: Other words for a prison include a gaol (pronounced like "jail"), penitentiary or correctional facility. In the US, the words "prison" and "jail" mean separate things. A US "jail" is run by a local government and holds people who have not yet had their trial or who have been convicted for a minor crime. A US "prison" or "penitentiary" is run by the state or federal government and holds people who are serving a long sentence for a serious crime. Outside of North America, "prison" and "jail" mean the same thing. There are lots of slang words for prisons.

paragraphs: Prisons are usually surrounded by walls and gates. There are usually many locked gates inside the prison to control the inmates.

paragraphs: The inmates sleep in small locked rooms called cells. Cells have a bunk bed, a toilet, and a sink. Inmates are allowed to leave their cell every day for exercise. Some inmates work in the prison during the day, either in a factory or doing cooking or cleaning. Law enforcement officers called prison guards watch the inmates. The manager of a prison is called the warden (US, Canada), superintendent (some parts of the US, India) or governor (UK, Australia).

paragraphs: Prisons usually also include other buildings and facilities, such as a chapel, a library, an exercise yard, a gymnasium, an infirmary (small hospital), visiting rooms (for visits from family and lawyers), kitchens, and accommodation for prison staff.

paragraphs: The level of security a prison has depends on the type of prison. A "maximum security prison" has even more protection than a regular prison. Some prisons in the United States have a section called "death row", where people who have been sentenced to death are kept in prison until their execution. On the other hand, an "open prison" is a prison where inmates can often travel out of the prison. These are used for prisoners who have been convicted of minor crimes, or who will soon be released.

paragraphs: The United Nations made the "Standard Minimum Rule" for human treatment for prisoners in 1955. Also the Article 10 of International Covenant on Civil and Political Rights also affirm the treatment with humanity for them in prison. In some prisons, people imprisoned for child sexual abuse are separated from other prisoners for their own safety.

paragraphs: There are four main ideas about what prisons should be used for:

paragraphs: A person who has been charged with a crime, but has not yet been convicted for it in a court, may be sent to prison if:

paragraphs: In some parts of the US, a person who is arrested may be held at a county jail until they decide whether to charge or release the person. In other places, a person who is arrested will be held at a police station, not a prison.

paragraphs: Male and female inmates are usually kept in separate locations, and often in separate prisons.

paragraphs: There are special prisons for people under the age of 18 who commit crimes. These inmates are called young offenders or juvenile offenders. These places will not always have the word "prison" in their name, instead having names like "Young Offenders' Institution".

paragraphs: Prisons are a controversial topic that people have different views about.

paragraphs: As of 2006, there are currently nine million people in prison in the world. The United States currently has the most people in prison; it has more than 2 million people in prison. In 2002, both Russia and China also had over 1 million people in prison. In 2003, the United Kingdom had 73,000 people in prison; France and Germany had a similar number of people in prison.

paragraphs: There are many books and poems about prisons or prison life, such as "The Count of Monte Cristo" by Alexandre Dumas, père and "The Ballad of Reading Gaol" by Oscar Wilde.

paragraphs: There are also movies that depict prison life, including:

paragraphs: There have also been television programs, such as "" (1979–1986), "Prison Break" (2005–2009), Lockup (2005 - present) and (2006 - present). A current TV show about a women's prison is Orange Is the New Black.


title: Mexico

paragraphs: Mexico (; official name: United Mexican States , ) is a country in North America. Mexico is south of Texas, California and other American states. Guatemala and Belize are south of Mexico. Mexico is between the Pacific Ocean and the Gulf of Mexico.

paragraphs: People living in Mexico or who are from there are called Mexicans. Most Mexican people speak Spanish. There are also Mexicans who speak Native American languages, like Nahuatl, Mayan, and Zapotec. The capital of Mexico is Mexico City.

paragraphs: Before the Europeans came, many Native American cultures existed in Mexico. The earliest was the Olmec culture in the south. The Olmecs are famous for the large stone heads they made. On the Yucatán peninsula lived the Mayans. The Mayans lived in city states ruled by kings. The Mayans were most powerful between 200 and 900 A.D. Another powerful empire belonged to Teotihuacan. Teotihuacan was a very large city, one of the largest at that time. After Teotihuacan declined the Toltecs became powerful. Things made by the Toltecs have been found from the southern parts of the U.S. all the way to Costa Rica. A famous Toltec god is Quetzalcoatl. The Toltec culture declined too, and it was succeeded by the Aztecs. The Aztecs called their own empire Mexico. A famous Aztec king was Moctezuma II.

paragraphs: In 1519 the Spanish explorer Hernán Cortés came to Mexico. The Aztecs thought he was the returned Quetzalcoatl, so they did not want to fight against him. Cortes allied himself with the enemies of the Aztecs. In 1521 they conquered the Aztec capital Tenochtitlan. The Aztec Empire became part of Spain. It was called New Spain.

paragraphs: In 1810 the Mexican priest Miguel Hidalgo started the Mexican war of independence. In 1821 the Spanish finally retreated and Mexico became independent. The first leader of independent Mexico was Agustin de Iturbide. He set up the First Mexican Empire and became emperor. But the Mexicans were not happy with him, and in 1823 the country became a republic.

paragraphs: A man who was very important in Mexico in the early 19th century was Antonio López de Santa Anna. He was the president of Mexico 11 times. When he became a dictator, Texas declared independence (1836). The Battle of the Alamo was part of this Texas Revolution. Between 1846 and 1848 there was war between Mexico and the United States. In this war Mexico lost its large northern areas, which became the southwestern United States. After this war Santa Anna was sent away to Venezuela.

paragraphs: Between 1858 and 1861 there was war again, between liberals and conservatives. The liberal Benito Juárez won the war and became president afterwards. Juarez stayed president until France invaded Mexico and made Maximilian of Habsburg emperor of the Second Mexican Empire. But Maximilian was very unpopular. After more war he was executed in 1867, and Juarez became president again.

paragraphs: Conservatives thought Juarez had too much power. In 1876 they ousted him, and made Porfirio Díaz, a general who had won a battle against the French, president. Porfirio Díaz made the country wealthier, but the poor people became poorer. Franciso I. Madero started the Mexican Revolution in 1910.

paragraphs: The next 10 years the country was in chaos. There were many presidents who ruled for a short time and all kinds of people fought against each other. Famous people from this period are Emiliano Zapata, Pancho Villa and Francisco I. Madero. When Álvaro Obregón became president in 1920 the fighting calmed down.

paragraphs: In 1929 President Plutarco Elías Calles founded the National Mexican Party, PNM. The party was later renamed Institutional Revolutionary Party, PRI. The party would rule for a very long time. Most PRI presidents were not popular, it was said that they were only president to become richer themselves. An exception was president Lázaro Cárdenas. He was president between 1934 and 1940.

paragraphs: After several decades more and more people became unhappy with the PRI. In 1968 security forces shot at protesters, this caused several hundred deaths and became known as the Tlatelolco massacre. Another uprising was in 1994 when Zapatistas rebelled in the province Chiapas.

paragraphs: Mainly through ballot box fraud the PRI managed to stay into power until 2000, when Vicente Fox of the National Action Party, PAN, was elected president. In total the PRI had governed Mexico for 71 years.

paragraphs: Mexico is a constitutional federal democracy ruled by a president. The president is elected every 6 years. The current president is Andrés Manuel López Obrador. Parliament has a Senate and House of Deputies.

paragraphs: Mexico is in the southern part of North America. It is roughly shaped like a triangle. Mexico is more than 3000 km (1,850 miles) long from northwest to southeast. Mexico is between two large seas: the Pacific Ocean in the West and the Gulf of Mexico and the Caribbean Sea in the East. Mexico has two large peninsulas. Baja California in the northwest, and Yucatán in the southeast. In central and western Mexico are the Sierra Madre mountains. In the Sierra Madre is the Pico de Orizaba, the highest mountain of Mexico. In central Mexico there are also a few volcanoes like the Popocatépetl and the Iztaccíhuatl. The Pico de Orizaba is also a volcano. In the north of Mexico are deserts. In the south are tropical rainforests. Some rivers in Mexico are the Río Bravo (known in the US as the Rio Grande), the Río Balsas, the Río Pánuco, and the Río Yaqui. Many animals are found in Mexico such as birds, jaguars and monkeys.

paragraphs: Mexico is the most populous Spanish-speaking country in the world. It is also the second most populous country in Latin America (after Brazil). 60% of Mexicans have Native American and European forefathers; these are called mestizos. Almost 30% of Mexicans are pure Native American and 10% are European. Most Mexicans (90%) speak Spanish. 10% of the Mexicans speak a Native American language, like Nahuatl, the language of the Aztecs, Maya or Zapotec. Most people in Mexico are Roman Catholic (89%) and 6% are Protestant. Other ethnic groups in Mexico are Arabs, Gypsies, Africans, Jews and Asians.


title: Atlantic Ocean

paragraphs: The Atlantic Ocean is the world's second largest ocean. It covers a total area of about . It covers about 20 percent of the Earth's surface. It is named after the god Atlas from Greek mythology. Its name means "Sea of Atlas."

paragraphs: The Atlantic formed when the Americas moved west from Eurasia and Africa. This began sometime in the Cretaceous period, roughly 135 million years ago. It was part of the break-up of the supercontinent Pangaea.

paragraphs: The east coast of South America is shaped somewhat like the west coast of Africa, and this gave a clue that continents moved over long periods of time (continental drift). The Atlantic Ocean is still growing now, because of sea-floor spreading from the mid-Atlantic Ridge, while the Pacific Ocean is said to be shrinking because the sea floor is folding under itself or subducting into the mantle.

paragraphs: The Atlantic Ocean is bounded on the west by North and South America. It connects to the Arctic Ocean through the Denmark Strait, Greenland Sea, Norwegian Sea and Barents Sea. It connects with the Mediterranean Sea through the Strait of Gibraltar.

paragraphs: In the southeast, the Atlantic merges into the Indian Ocean. The 20° East meridian defines its border.

paragraphs: In the southwest, the Drake Passage connects it to the Pacific Ocean. The Panama Canal links the Atlantic and Pacific.

paragraphs: The Atlantic Ocean is second in size to the Pacific. It occupies an area of about . The volume of the Atlantic, along with its adjacent seas (the seas next to it), is 354,700,000 cubic kilometres.

paragraphs: The average depth of the Atlantic, along with its adjacent seas, is . The greatest depth is Milwaukee Deep near Puerto Rico, where the Ocean is deep.

paragraphs: The Atlantic Ocean has important ocean currents. One of these, called the Gulf Stream, flows across the North Atlantic. Water gets heated by the sun in the Caribbean Sea and then moves northwest toward the North Pole. This makes France, Ireland, Britain, Iceland, and Norway in Europe much warmer in winter than Newfoundland and Nova Scotia in Canada. Without the Gulf Stream, the climates of northeast Canada and northwest Europe might be the same, because these places are about the same distance from the North Pole.

paragraphs: There are currents in the South Atlantic too, but the shape of this sea means that it has less effect on South Africa.

paragraphs: The main feature of the Atlantic Ocean's seabed is a large underwater mountain chain called the Mid-Atlantic Ridge. It runs from north to south under the Ocean. This is at the boundary of four tectonic plates: Eurasian, North American, South American and African. The ridge extends from Iceland in the north to about 58° south.

paragraphs: The salinity of the surface waters of the open ocean ranges from 3337 parts per thousand and varies with latitude and season.


title: Mercury (element)

paragraphs: Mercury, also known as quicksilver or hydrargyrum, is a chemical element. Its symbol on the periodic table is Hg, and its atomic number is 80. Its atomic mass is 200.59.

paragraphs: The symbol "Hg" stands for its Latinized Greek name "hydrargyrum", meaning watery or liquid silver.

paragraphs: No one has the credit for finding mercury. It was known in ancient times. Mercury was found in Egyptian tombs that are from 2000 BC.

paragraphs: Chinese people also knew it from long ago. In China and Tibet, people thought using mercury would make them live longer and have better health. One of China's emperors, Qín Shǐ Huáng Dì, is said to have been buried in a tomb with rivers of flowing mercury. He died from drinking a mixture of mercury and powdered jade because he wanted to live forever. However, this only made him die of liver failure, poisoning, and brain death. The ancient Greeks used mercury in ointments. The Egyptians and the Romans used it in cosmetics. These cosmetics sometimes hurt and made faces uglier.

paragraphs: Mercury is a silvery-white liquid post-transition metal. The reason for mercury being a liquid is complex. It is heavy; a chunk of iron can float on mercury. Compared to other metals, it does not conduct heat well. However, it conducts electricity fairly well. Mercury is the only metal with a known melting point (−38.83 °C) lower than caesium. Mercury is one of the two elements that are liquids at standard temperature and pressure. Bromine is the other one.

paragraphs: Mercury may be seen as a transition metal, but it is normally seen as a post-transition metal. It is in Group 12 of the periodic table. Mercury has seven stable (nonradioactive) isotopes. Hg is the most common isotope. Mercury makes a blue to ultraviolet color in a tube when a spark is passed through it. The ultraviolet light can kill germs or light fluorescent lamps.

paragraphs: Mercury is an unreactive metal. It does not corrode in air unless hydrogen sulfide is also there, similar to silver. Mercury can oxidize to mercury(II) oxide when heated in air. If it is heated further, it decomposes into mercury and oxygen again. It does not dissolve in ordinary acids, but can dissolve in oxidizing acids to make mercury salts. It can make amalgams when mixed with most metals, like aluminium, gold, and zinc. Iron, tantalum, tungsten, and platinum do not make amalgams with mercury. Iron flasks were used to trade mercury because of this.

paragraphs: Mercury can dissolve large amounts of aluminium metal, making it dangerous to transport in aluminium containers. The thin layer of oxide on aluminium stops it from amalgamating (making an amalgam with) aluminium, but the oxide coating can be damaged to expose the metal. Then the aluminium metal is dissolved and oxidizes to aluminium oxide. The aluminium oxide forms a solid and releases the mercury, which amalgamates more aluminium. This process keeps repeating until a large amount of aluminium is dissolved.

paragraphs: Mercury forms chemical compounds in 2 oxidation states: +1 and +2. Mercury(I) compounds are weak oxidizing agents and weak reducing agents. Most of them are colorless. They easily disproportionate to mercury(II) compounds and mercury metal. They react with oxygen in the air to make mercury(II) compounds. Many mercury(I) compounds do not dissolve in water. Mercury(I) chloride is one of the most common mercury(I) compounds. Mercury(II) compounds are strong oxidizing agents and very corrosive. Mercury(II) compounds are red, yellow, or colorless. Mercury(II) oxide and mercury(II) chloride are the most common mercury(II) compounds in the laboratory.

paragraphs: One thing they have in common is that they are all toxic. The soluble ones are more toxic than the insoluble ones.

paragraphs: Also known as mercurous compounds, these are weak reducing agents and weak oxidizing agents. Most of them do not dissolve in water, making them less toxic than mercury(II) compounds. Most of them are colorless or yellow.

paragraphs: Also known as mercuric compounds, these are strong oxidizing agents. Most of them dissolve in water, making them very toxic. They are colorless or red.

paragraphs: These contain mercury reacted with a organic molecule. They are even more toxic than other mercury compounds since they get absorbed very easily.

paragraphs: Mercury is a rare metal. It is about as common as silver. Mercury is not expensive like silver because the mercury is very easy to get from the places where it is found. Mercury can be found in elemental (liquid) form in nature, but this is not common. Mercury as an element is the only liquid that is recognized as a mineral by the International Mineralogical Association. It is most often found in the form of cinnabar, a mercury(II) sulfide mineral. The biggest deposits of cinnabar used to be found in Spain, but now are found in China. It also occurs in other minerals like calomel, a mercury(I) chloride mineral.

paragraphs: China and Kyrgyzstan are the two main makers of mercury. Mines in Italy, the United States, and Mexico have been closed. China is opening more mines because the European Union wants to use fluorescent lights, which need mercury.

paragraphs: Mercury is made by roasting cinnabar in a furnace. The sulfide is oxidized to sulfur dioxide, leaving mercury behind.

paragraphs: Mercury has been used in dental fillings until it was replaced with safer materials. They are an amalgam of mercury with another element. An organic mercury compound called thiomersal is used to preserve vaccines. Merbromin, another organic mercury compound, is used as an antiseptic. It has been banned in some countries like the US.

paragraphs: Mercury(I) chloride (also known as calomel or mercurous chloride) has been used as a diuretic, skin disinfectant, and laxative. Together with other mercury compounds, Mercury(II) chloride (also known as mercuric chloride or corrosive sublimate) was used to treat syphilis. The problem with this was that mercury(II) chloride is very toxic. Sometimes the symptoms of its toxicity were confused with those of the syphilis it was believed to treat. It is also used as a disinfectant. , a pill or syrup in which mercury is the main ingredient, was prescribed throughout the 1800s for different conditions such as constipation, depression, child-bearing and toothaches. In the early 20th century, mercury was given to children once a year as a laxative and dewormer. Teething powders for infants also had it in them.

paragraphs: Since the 1930s some vaccines have contained the preservative thiomersal. In the body, this is changed to ethylmercury. At first it was thought that this mercury-based preservative can cause or trigger autism in children, but scientific studies could not show such a link. Because of this, thiomersal has been removed from most U.S. vaccines recommended for children six years of age and under. There are certain exceptions to this rule for influenza vaccines. In some cases, vaccines may still have very small amounts of thiomersal in them.

paragraphs: Cinnabar is still an important component of traditional Chinese, Tibetan, and Ayurvedic medicine. Certain countries do not allow the use of mercury or its compounds in drugs. For this reason, cinnabar has recently been replaced with less toxic products.

paragraphs: Today, the use of mercury in medicine has greatly declined in all respects, especially in developed countries. Thermometers and blood pressure devices using mercury were invented in the early 18th and late 19th centuries, respectively. Now their use is declining and has been banned in some countries, states and medical institutions. In 2002, the U.S. Senate passed legislation to phase out the sale of non-prescription mercury thermometers. In 2003, Washington and Maine became the first states to ban mercury blood pressure devices. Mercury compounds are in some over-the-counter drugs, including topical antiseptics, stimulant laxatives, diaper rash ointment, eye drops, and nasal sprays. The FDA has “inadequate data to establish general recognition of the safety and effectiveness” of the mercury in these products. Mercury is still used in some diuretics, although other things can be used for most therapeutic uses.

paragraphs: In 2017 the worldwide use of mercury was less than half of what it was in 1980.

paragraphs: Mercury is liquid at room temperature, and fumes of mercury are very poisonous. Ingested elemental mercury is less dangerous. The biggest problems are organic mercury compounds which are eaten with food. As with other heavy metals, inorganic compounds such as mercury(II) nitrate are also highly toxic by ingestion (eating) or inhalation (breathing in) of the dust. Mercury can cause both chronic and acute poisoning.

paragraphs: In the year 1810, over 200 people died of mercury poisoning on the ship "Triumph" because a barrel of mercury had leaked.

paragraphs: Mercury is extremely poisonous and has to be used carefully. When mercury is spilled, there are special ways to clean it up. Smaller drops should be combined to a larger drop on hard surfaces to be removed more easily (for example, being pushed into a bag that can be thrown away). Vacuum cleaners and brooms should not be used. This is because they can spread mercury even more. Afterwards, elements such as sulfur or zinc powder should be sprinkled over the place, then collected and cleaned away. It is not easy to clean mercury entirely off clothing, so it is better not to use them anymore. Breathing in mercury vapor is also very dangerous.


title: Africa

paragraphs: Africa is the second largest continent in the world. It makes up about a fifth of the world's land. It is surrounded by large areas of water. There are 54 fully recognised and independent countries in Africa, and 14.7% (1.216 billion) of the world's population lives there. It is thought to be the continent where the first humans evolved.

paragraphs: The history of Africa begins from the first modern human beings and leads to its present difficult state as a politically developing continent.

paragraphs: Africa's ancient historic period includes the rise of Egyptian civilization, the further development of societies outside the Nile River Valley and the interaction between them and civilizations outside of Africa. In the late 7th century North and East Africa were heavily influenced by the spread of Islam. That led to the appearance of new cultures such as those of the Swahili people, and the Mali Empire, whose king, Musa Keita I, became one of the richest and most influential people of the early 14th century. This also led to an increase in the slave trade that had a very bad influence for the development of the whole continent until the 19th century.

paragraphs: Slavery has long been practised in Africa. Between the seventh and twentieth centuries, the Arab slave trade took 18 million slaves from Africa via trans-Saharan and Indian Ocean routes.

paragraphs: Between the fifteenth and the nineteenth centuries (500 years), the Atlantic slave trade took an estimated 7–12 million slaves to the New World.

paragraphs: Between 1808 and 1860, the British Navy captured approximately 1,600 slave ships and freed 150,000 Africans who were aboard.

paragraphs: In the late nineteenth century, the European powers occupied much of the continent, creating many colonial and dependent territories. They left only three fully independent states: Darwiish State, (also spelled Daraawiish State), Ethiopia (known to Europeans as "Abyssinia"), and Liberia. Taleh, then capital of Darawiish, was the only African capital city which survived the scramble for Africa.

paragraphs: Egypt and Sudan were never formally incorporated into any European colonial empire. However, after the British occupation of 1882, Egypt was effectively under British administration until 1922.

paragraphs: African independence movements had their first success in 1951 when Libya became the first former colony to become independent. Modern African history has been full of revolutions and wars as well as the growth of modern African economies and democratization across the continent.

paragraphs: A civil war in the Democratic Republic of the Congo (formerly Zaire) began in 1998. Neighbouring African countries have become involved. Since the conflict began, 5,5 million are estimated to have died because of it.

paragraphs: Political associations such as the African Union offer hope for greater co-operation and peace between the continent's many countries.

paragraphs: From north to south, Africa has most types of climate. In sequence from the north:

paragraphs: Running north-east to the south is the East African Great Rift Valley. This has mountains, volcanoes, deep rifts and valleys, rivers and lakes.

paragraphs: In fact Africa has examples of most of the Earth's climate types.

paragraphs: Much of North Africa is dry and hot: it is dominated by the Sahara Desert and does not receive much rain. In Saharan Africa there are few rivers or other water sources. Underground water sources, such as springs are very important in the desert. These often form oases. An oasis is an area of vegetation (plant life) surrounded by desert.

paragraphs: In that part of the world the wind comes mostly from the east. That does bring rain, but the Himalayas and the Tibetan Plateau blocks the monsoon rain and prevents it getting to North Africa. Also, the Atlas Mountains near the north coast

paragraphs: of Africa prevent rain from coming in from the north. That is another rain shadow.

paragraphs: These two rain shadows are mainly responsible for the Sahara desert.

paragraphs: Conditions and winds are different further south, where huge amounts of rain falls near the equator. The equator runs across the middle of Africa (see red line drawn on map). That means much of Africa is between the two tropics:

paragraphs: Africa has a lot of wildlife. There are many types of animals there. In particular, it is now the only continent that has many native species of large mammals. Some of them occur in very large numbers. There are antelope, buffalo, zebra, cheetah, elephant, lion, giraffe, rhinoceros, apes, hyaena, and a lot more. Over 2,000 types of fish live in African lakes and rivers.

paragraphs: The African Union (AU) is an international organisation. It aims to transform the African Economic Community, a federated commonwealth, into a state under established international conventions. The African Union has a parliamentary government, known as the African Union Government, consisting of legislative, judicial and executive organs. It is led by the African Union President and Head of State, who is also the President of the Pan African Parliament. A person becomes President of the AU by being elected to the PAP, and then gaining majority support in the PAP.

paragraphs: Extensive human rights abuses still occur in several parts of Africa, often under the oversight of the state. Most of such violations occur for political reasons, often as a side effect of civil war. Countries where major human rights violations have been reported in recent times include Uganda, Sierra Leone, Liberia, Sudan, Zimbabwe, and Côte d'Ivoire.

paragraphs: People who come from Africa are called Africans. People in the north are called North Africans and people in the south are caled South Africans. Languages in eastern Africa include Swahili, Oromo and Amharic. Languages in western Africa include Lingala, Igbo and Fulani. The most populated country in Africa is Nigeria.

paragraphs: Countries with significant African descendents outside Africa: