title: Cosmology

paragraphs: Cosmology is the branch of astronomy that deals with the origin, structure, evolution and space-time relationships of the universe. NASA defines cosmology as "The study of the structure and changes in the present universe". Another definition of cosmology is "the study of the universe, and humanity's place in it".

paragraphs: Modern cosmology is dominated by the Big Bang theory, which brings together observational astronomy and particle physics.

paragraphs: Though the word "cosmology" is recent (first used in 1730 in Christian Wolff's "Cosmologia Generalis"), the study of the universe has a long history.

paragraphs: Until recently, people thought that the universe was the Milky Way. They thought this because they could only see the planets up to Saturn and stars. With the invention of the telescope, our universe got bigger. Even in the 20th century, people thought that the Milky Way was the universe. With the Hubble Space Telescope, people could see things far away.


title: Church (building)

paragraphs: A church is a building that was constructed to allow people to meet to worship together. These people are usually Christians, or influenced by Christianity. Some other religious groups also call their religious buildings churches.

paragraphs: Depending on the number of people that are in a community, the churches come in different sizes. Small churches are called chapels. The churches in a particular geographical area form a group called the diocese. Each diocese has a cathedral. In most cases, the cathedral is a very big church. Cathedrals are the seat of bishops.

paragraphs: In the early days of Christianity people had to worship in secret. Christian worship was not allowed in the Roman empire, so Christians had to meet in a secret place. Sometimes they met in people’s houses or barns, sometimes they met underground. The first places that were built for Christian worship were small chapels that were cut into a rock where people could worship without being discovered.

paragraphs: After the death of the Roman emperor Constantine in 337 A.D. Christians were allowed to have buildings to worship in. These first churches were built on a similar plan to Roman basilicas. This plan was later used for the fine Gothic cathedrals and churches that were built at the end of the Middle Ages.

paragraphs: There are several parts in the architecture of a church. Not all churches will have all these parts:

paragraphs: In Roman Catholic churches there is always a stoup (bowl) of holy water near the entrance of the church. This tradition comes from the fact that Roman basilicas had a fountain for washing in front of the entrance. The font is a bowl where people (often babies) are baptized. This is also near the entrance of the church. This is a symbol of the fact that it is welcoming the people into the Christian church.

paragraphs: Traditionally the nave has long benches for the congregation to sit on. These are called pews. Some churches may now have replaced their pews with chairs so that they can be moved about for different occasions. At the front of the nave is the pulpit where the priest preaches (these talks are called “sermons”). There is also a lectern (like a large music stand) from where the lessons (the Bible readings) are read.

paragraphs: If there are aisles along the side of the nave there will be pillars which hold up the roof. In large churches or cathedrals there may be a row of little arches along the top of these pillars. This is called the triforium. Over the triforium is the clerestory which is a row of windows high up in the church wall.

paragraphs: The chancel is the most holy part of the church, and this is why it is often separated from the nave by a screen which can be made of wood or stone, or occasionally iron. The congregation can see through the screen. On the top of the screen there may be a cross. This is called a rood (pronounce like “rude”) screen. Priests used to climb up a staircase to the top of the rood screen to read the epistle and the gospel. Sometimes people sang from there.

paragraphs: Inside the chancel are the benches where the choir sit. These are called choir stalls. They are on both sides. The two sides of the choir sit facing one another. The choir members who sit on the left (north side) are called “cantoris” (the side where the “cantor” sits) and those on the right (south side) are called “decani” (the side where the deacon sits). In some large churches or cathedrals the seats for the priests tip up. The top of these seats, when they are tipped up, are called misericords (from the Latin word for “mercy”). This is because the priests or monks were able to lean against them when they got tired if they had to stand up for a long time.

paragraphs: Sometimes there are holes in the walls of the screen so that the congregation can see through. These are called squints. If there is a recess in the wall it is called an aumbry. It is a cupboard for communion wine and bread that have been consecrated by a priest.

paragraphs: The altar may be right at the east end of the church, but in larger churches or cathedrals it is often much farther forward. In that case the very east end is called an apse. Sometimes it is a separate chapel called the “Lady Chapel”.

paragraphs: The design of churches changed a lot during the course of history. Often churches were made bigger. When this happened there may be a mixture of architectural styles. These styles vary a lot in different countries.

paragraphs: In English churches there were several different periods of architecture:

paragraphs: In the 1600s, churches were built in a variety of styles. Often they copied some of the older styles. After the Great Fire of London many new churches were built by the architect Sir Christopher Wren. They were built in the classical style. Churches continued to be built in later centuries like this, but also the Gothic style continued to be used.

paragraphs: Modern churches often do not have the traditional cross-shape. It is difficult for the congregation to see and hear what is happening in the chancel. Modern churches bring the congregation, choir and priests in closer touch. An example is the round design for the Church of Christ the Cornerstone in Milton Keynes. Modern churches are often simpler but with a warmer character than the Gothic churches. Many have beautiful mosaic glass windows. Coventry Cathedral is a famous example of a modern church building.


title: City

paragraphs: A city is a populous community that may include structures, buildings and landmarks. Examples of cities in the United States include Dallas, Phoenix, Omaha, Kansas City, St. Louis, San Francisco, Boston, Atlanta, New York City, Jersey City, Providence, New Orleans, Las Vegas, Chicago, Los Angeles, Indianapolis, Detroit, Milwaukee and more.

paragraphs: A city has many buildings and streets. It has houses or apartments for many people to live, shops where they may buy things, places for people to work and a government organisation to run the city, and to keep law and order in the city. People live in cities because it is easy for them to find and do the things they want there. A city usually has a "city centre" where government and business take place, and places called suburbs where people live around the outside of the centre.

paragraphs: Cities in the US are usually very-left leaning. The best examples of these would be New York, New York, and Washington. In the state of Louisiana, for example, the only Democratic delegate in US Congress who is a Democrat was elected from a district comprising in New Orleans. Below is a list of states, and the major city/cities that provide much of the liberal support in them:

paragraphs: "If you know any others, add to this list!"

paragraphs: There is no rule that is used all over the world to decide why some places are called "city" and other places are called "town".

paragraphs: In American English, people often call all places where many people live cities. (See below: Size of cities)

paragraphs: The sizes of cities can be very different. This depends on the type of city that it is. Cities that were built hundreds of years ago and which have not changed much, are very much smaller than modern cities. There are two main reasons. One reason is that old cities often have a city wall, and most of the city is inside it. Another important reason is that the streets in old cities are often narrow. If the city got too big, it was hard for a cart carrying food to get to the market place. People in cities need food, and the food always has to come from outside the city. Cities that were on a river like London could grow much bigger than cities that were on a mountain like Sienna in Italy, because the river made a transport route for carrying food and other goods, as well as for transporting people. London has been changing continually for hundreds of years, while Siena, which was a very important city in the 1300s has changed very little in 700 years. Modern cities with modern transport systems can grow very large, because the streets are wide enough for cars, buses and trucks, and there are often railway lines as well.

paragraphs: In the US, the word city is often used for towns that are not very big. When the first European people went to America, they gave the name "city" to new places. They hoped the places would be great cities in the future. For example, Salt Lake City was the name given to a village of 148 people. When they started building the town they made street plans and called it Great Salt Lake City (for the nearby Great Salt Lake). Now, 150 years later, it really is a big city.

paragraphs: In modern times many cities have grown bigger and bigger. The whole area is often called a ""metropolis"" and can sometimes includes several small ancient towns and villages. The "metropolis" of London includes the City of London, the City of Westminster and many old villages such as Notting Hill, Southwark, Richmond, Greenwich and etc. The part that is officially known as the "City of London" only takes up one square mile. The rest is known as "Greater London". Many other cities have grown in the same way.

paragraphs: These giant cities can be exciting places to live, and many people can find good jobs there, but modern cities also have many problems. Many people cannot find jobs in the cities and have to get money by begging or by crime. Cars, factories, and waste create a lot of pollution that makes people sick. the smallest city is Urban history

paragraphs: Urban History is history of civilization. The first cities were made in ancient times, as soon as people began to create civilization. Famous ancient cities which fell to ruins included Babylon, Troy, Mycenae and Mohenjo Daro.

paragraphs: Benares in northern India is one among the ancient cities which has a history of more 3000 years. Other cities that have existed since ancient times are Athens in Greece, Rome and Volterra in Italy, Alexandria in Egypt and York in England.

paragraphs: In Europe, in the Middle Ages, being a city was a special privilege, granted by nobility. Cities that fall into this category, usually had (or still have) city walls. The people who lived in the city were privileged over those who did not. Medieval cities that still have walls include Carcassonne in France, Tehran in Iran, Toledo in Spain and Canterbury in England.

paragraphs: In the United Kingdom, a city is a town which people have always called a city, or which has got the name "city" status by royal charter (a special paper from the king or queen). Cities usually get this because they have a special number of people or are important. In the past, cities got that name if they had a cathedral or a university. Some cathedral cities, for example St David's, are small, and people do not normally think of them as cities. Cities that became cities because of their university generally grow because more people move there to be educated at the university colleges. The university cities of Oxford and Cambridge are famous throughout the world. The largest city is Shanghai, while the fastest growing is Dubai. The smallest city in the UK is Wells.

paragraphs: These cities have more than 10 million people:


title: Cooking

paragraphs: Cooking is a process to make food ready to eat by heating it. Cooking can kill bacteria that may be in the food.

paragraphs: Raw food is food that is not cooked. Some foods are good to eat raw. Other foods are not good for the body when they are raw, so they must be cooked. Some foods are good to eat either raw or cooked.

paragraphs: Cooking is often done in a kitchen using a stove or an oven. It can also be done over a fire (for example, over a campfire or on a barbecue).

paragraphs: The heat for cooking can be made in different ways. It can be from an open fire that burns wood or charcoal. It can be on a stove or in an oven that uses propane, natural gas, or electricity.

paragraphs: There are several different ways to cook food. Boiling cooks food in hot water. Frying (deep or shallow) cooks food in hot butter, fat or oil. Baking and roasting cook food by surrounding it with hot air. Grilling means cooking food on a metal grill that has heat under it.

paragraphs: People often cook meat by boiling, roasting, frying, or grilling it. Some foods such as bread or pastries are usually baked.

paragraphs: Usually food is cooked in some kind of pot or pan. Sometimes people cook food by putting it directly into the fire, or by wrapping the food in leaves before they put it into the fire.

paragraphs: A person whose job it is to cook food may be called a "cook" or a "chef". The word "cooker" means a machine or tool that a cook might use to cook food. Rice cookers and pressure cookers are examples.


title: Chat

paragraphs: To chat is to talk about ordinary things that are not very important. A person can chat with another person, or to many people. People also use this word now for parts of the Internet where we can talk with many different people at the same time. Usually, people chat on the Internet in a chat room or messaging service like AOL Instant Messenger (AIM), Yahoo Messenger Windows Live Messenger or Tencent QQ. There are also programs which let people use different messaging services from one program, such as Pidgin.


title: Cup

paragraphs: A cup is any kind of container used for holding liquid and drinking. These include:


title: Crime

paragraphs: A crime (or misdemeanor or felony) is an act done by a person which is against the laws of a country or region. A person who does this is called a criminal.

paragraphs: The basic idea of what things are called "crimes" is that they are thought to be things that might cause a problem for another person. Things like killing another person, injuring another person, or stealing from another person are crimes in most countries. Also, it can be a crime to have or sell contraband such as guns or illegal drugs.

paragraphs: When some criminals make money from crime, they try to stop the police finding out where the money came from by money laundering. Men and boys commit many more crimes than women and girls.

paragraphs: There are various levels of crimes. In some jurisdictions they are:

paragraphs: Different countries have different ideas of what things are crimes, and which ones are the worst. Some things that are crimes in one country are not crimes in other countries. Many countries get their ideas of what things are crimes from religions or controversial events which cause a law to be quickly created. For example, a religious Taboo might say eating a particular food is a crime. When automobiles became numerous, they killed or hurt many people in road accidents, so new laws were made for them.

paragraphs: In many countries, if people say they made or wrote a book, movie, song, or Web page that they did not really make or write, it is a crime against copyright laws. In many countries, helping to grow, make, move, or sell illegal drugs is a crime.

paragraphs: In most countries, police try to stop crimes and to find criminals. When the police find someone who they think might be a criminal, they usually hold the person in a jail. Then, usually, a court or a judge decides if the person really did a crime. If the court or judge decides that the person really did it, then he or she might have to pay a fine or go to prison. Sometimes the judge might decide that the criminal should be executed (killed). This is called Capital punishment (or the "Death Penalty"). There are countries in the world that execute criminals, and others that do not.

paragraphs: In many countries, two conditions must exist for an act to be thought of as a crime:

paragraphs: Both must be present for the act to be thought of as a crime.


title: Time Cube

paragraphs: Time Cube was a personal website created on 1997 by Otis Eugene Ray. On that website, Ray explained his theory of everything, known as "Time Cube". It described the planet Earth as having a cubic symmetry, and time as rotating four "corners". He also said that all of modern physics is wrong. Scientists reject these ideas, saying that they make no sense and cannot be tested.

paragraphs: The Time Cube website was written in an angry and hateful voice. On his site, Ray said that not believing in Time Cube would be "stupid and evil". Some of the comments were racist and discriminatory, especially against black people and Jews. There were also many comments against gay people. Many people found the site to be difficult to understand.

paragraphs: Ray spoke about Time Cube at the Massachusetts Institute of Technology in January 2002. At MIT, a professor tried to cancel the lecture before it took place. Ray believed this is proof of a conspiracy to keep information about Time Cube hidden. Ray also spoke about Time Cube at the Georgia Institute of Technology in April 2005.

paragraphs: Otis Eugene Ray died on March 18, 2015. He was 87 years old. The website went down on August 2015. It was last archived by the Wayback Machine on January 12, 2016.


title: Census of Marine Life

paragraphs: The Census of Marine Life is a ten-year survey of life in the oceans, starting in 2000. Its head is Ron O'Dor of Dalhousie University in Halifax, Nova Scotia, Canada. It uses data from researchers all over the world. More than 70 nations are involved and over a billion US dollars will be spent on it.

paragraphs: It is a major work of marine ecology. It was founded by J. Frederick Grassle.

paragraphs: It is trying to do what the World Wide Fund for Nature (WWF) and National Geographic Society did for terrestrial ecoregions - say exactly what is alive on the planet.


title: Maize

paragraphs: Maize or Indian corn (called corn in some countries) is "Zea mays", a member of the grass family "Poaceae". It is a cereal grain which was first grown by people in ancient Central America. It is now the third most important cereal crop in the world. However, little of this maize is eaten directly by humans. Most is used to make corn ethanol, animal feed and other maize products, such as corn starch and corn syrup.

paragraphs: Maize is a leafy stalk whose kernels have seeds inside. It is an angiosperm, which means that its seeds are enclosed inside a fruit or shell. It is has long been a staple food by many people in Mexico, Central and South America and parts of Africa. In Europe and the rest of North America, maize is grown mostly for use as animal feed. In Canada and the United States, maize is commonly referred to as "corn".

paragraphs: Centuries of cross breeding have produced larger plants, and specialized varieties. Corn has become an important ingredient in American foods through the use of corn starch. People have long eaten sweet corn and popcorn with little processing, and other kinds after processing into flour for making cornbread, tortillas, and other artificial foods.

paragraphs: Maize has been a fruitful model organism for research in genetics for many years: see Barbara McClintock. Research has shown that artificial selection developed maize from a Mexican plant called Teosinte.

paragraphs: There are five species and many subspecies in the genus. They are all plants similar to the cultivated maize, with less developed cobs. The wild ones are sometimes called teosintes, and they are all native to Mesoamerica.


title: Civics

paragraphs: Civics is the study of government. It most often refers to studying government in high school to prepare to be a good citizen. In college, civics is usually called political science. Since a city has the most unsimple government problems, the word for this study is like that for city.


title: Calculus

paragraphs: Calculus is a branch of mathematics that helps us understand changes between values that are related by a function. For example, given a formula indicating how much money one gets every day, calculus would help one understand related formulas, such as how much money one has in total, and whether one is getting more or less money than before. Many of these formulas are functions of time, and one way to think of calculus is to see it as a study of functions of time.

paragraphs: There are two different types of calculus. Differential calculus divides things into small ("different") pieces, and tells us how they change from one moment to the next, while integral calculus joins ("integrates") the small pieces together, and tells us how much of something is made, overall, by a series of changes. Calculus is used in many different areas such as physics, astronomy, biology, engineering, economics, medicine and sociology.

paragraphs: In the 1670s and 1680s, Sir Isaac Newton in England and Gottfried Leibniz in Germany figured out calculus at the same time, working separately from each other. Newton wanted to have a new way to predict where to see planets in the sky, because astronomy had always been a popular and useful form of science, and knowing more about the motions of the objects in the night sky was important for navigation of ships. Leibniz wanted to measure the space (area) under a curve (a line that is not straight). Many years later, the two men argued over who discovered it first. Scientists from England supported Newton, but scientists from the rest of Europe supported Leibniz. Most mathematicians today agree that both men share the credit equally. Some parts of modern calculus come from Newton, such as its uses in physics. Other parts come from Leibniz, such as the symbols used to write it.

paragraphs: They were not the first people to use mathematics to describe the physical world — Aristotle and Pythagoras came earlier, and so did Galileo Galilei, who said that mathematics was the language of science. But both Newton and Leibniz were the first to design a system that describes how things change over time, and can predict how they will change in the future.

paragraphs: The name "calculus" was the Latin word for a small stone the ancient Romans used in counting and gambling. The English word "calculate" comes from the same Latin word.

paragraphs: Differential calculus is used to find the rate of change of a variable—compared to another variable.

paragraphs: In the real world, it can be used to find the speed of a moving object, or to understand how electricity and magnetism work. It is very important for understanding physics—and many other areas of science.

paragraphs: Differential calculus is also useful for graphing. It can be used to find the slope of a curve, and the highest and lowest points of a curve (these are called the maximum and minimum, respectively).

paragraphs: Variables can change their value. This is different from numbers because numbers are always the same. For example, the number 1 is always equal to 1, and the number 200 is always equal to 200. One often write variables as letters such as the letter x: "x" can be equal to 1 at one point and 200 at another.

paragraphs: Some examples of variables are distance and time, because they can change. The speed of an object is how far it travels in a particular time. So if a town is 80 kilometres (50 miles) away and a person in a car gets there in one hour, they have traveled at an average speed of 80 kilometres (50 miles) per hour. But this is only an average: maybe they travelled faster at some times (say on a highway), and slower at other times (say at a traffic light or on a small street where people live). Certainly it is more difficult for a driver to figure out a car's speed using only its odometer (distance meter) and clock—without a speedometer.

paragraphs: Until calculus was invented, the only way to work this out was to cut the time into smaller and smaller pieces, so the average speed over the smaller time would get closer and closer to the actual speed at a point in time. This was a very long and hard process, and had to be done each time people wanted to work something out.

paragraphs: A very similar problem is to find the slope (how steep it is) at any point on a curve. The slope of a "straight" line is easy to work out — it is simply how much it goes up or down ("y" or vertical) divided by how much it goes across ("x" or horizontal). On a "curve", however, the slope is a variable (has different values at different points) because the line bends. But if the curve was to be cut into very, very small pieces, the curve at the point would look almost like a very short straight line. So to work out its slope, a straight line can be drawn through the point with the same slope as the curve at that point. If this is done exactly right, the straight line will have the same slope as the curve, and is called a tangent. But there is no way to know (without complex mathematics) whether the tangent is exactly right, and our eyes are not accurate enough to be certain whether it is exact or simply very close.

paragraphs: What Newton and Leibniz found was a way to work out the slope (or the speed in the distance example) exactly, using simple and logical rules. They divided the curve into an infinite number of very small pieces. They then chose points on either side of the range they were interested in and worked out tangents at each. As the points moved closer together towards the point they were interested in, the slope "approached" a particular value as the tangents approached the real slope of the curve. The particular value it approached was the actual slope.

paragraphs: Given a function formula_1. "f" is short for function, so this equation means "y is a function of x". This tells us that how high y is on the vertical axis depends on what x (the horizontal axis) is at that time. For example, with the equation formula_2, we know that if formula_3 is 1, then formula_4 will be 1; if formula_3 is 3, then formula_4 will be 9; if "formula_3" is 20, then "formula_4" will be 400. The slope of the tangent line produced using this method here is formula_9, or 2 multiplied by "formula_3". So we know without having to draw any tangent line at any point on the curve formula_11 that the derivative, often written as formula_12 (marked with the prime symbol), will be formula_9 at any point. This process of working out a slope using limits is called differentiation, or finding the derivative.

paragraphs: The way to write the derivative in mathematics is

paragraphs: Leibniz came to the same result, but called h "formula_15", which means "with respect to x". He called the resulting change in formula_16 "formula_17", which means "a tiny amount of y". Leibniz's notation is used by more books, because it is easy to understand when the equations become more complicated. In Leibniz notation:

paragraphs: Mathematicians have grown this basic theory to make simple algebra rules—which can be used to find the derivative of almost any function.

paragraphs: Integral calculus is the process of calculating the area underneath a graph of a function. An example is calculating the distance a car travels: if one knows the speed of the car at different points in time and draw a graph of this speed, then the distance the car travels will be the area under the graph.

paragraphs: The way to do this is to divide the graph into many very small pieces, and then draw very thin rectangles under each piece. As the rectangles become thinner and thinner, the rectangles cover the area underneath the graph better and better. The area of a rectangle is easy to calculate, so we can calculate the total area of all the rectangles. For thinner rectangles, this total area value "approaches" the area underneath the graph. The final value of the area is called the "integral" of the function.

paragraphs: In mathematics, the integral of the function "f(x)" from "a"  to "b", is written as

paragraphs: The main idea in calculus is called the fundamental theorem of calculus. This main idea says that the two calculus processes, differentiation and integration, are inverses of each other. That is, a person can use differentiation to undo an integration process. Also, a person can use integration to undo a differentiation. This is just like using division to "undo" multiplication, or addition to "undo" subtraction.

paragraphs: In a single sentence, the fundamental theorem runs something like this: "The derivative of the integral of a function "f" is the function itself".

paragraphs: Calculus is used to describe things that change, like things in nature. It can be used for showing and learning all of these:


title: Coin

paragraphs: A coin is normally a round piece of metal that is used as currency, or money. Coins have been made for about 2600 years; the first place to make coins was Lydia (modern Turkey).[citation needed] These coins were made of Precious metals and allowed people to trade with a standard amount of metal.

paragraphs: Most people use coins as currency. They usually have lower value than banknotes. Most are made in government mints.

paragraphs: Many coins have unique or complicated decorations; one side often has the picture of a famous or important person's head on it.

paragraphs: The different decorations on each side of a coin might be used to decide things randomly. This is called "tossing a coin". A person can throw the coin into the air and catch it. You then look at which side is facing up. If the head is facing up it is called "heads", if the other side is facing up it is called "tails". Before tossing the coin someone has to decide what each side means. Tossing a coin can be a type of gambling, which is illegal (against the law) in some countries.

paragraphs: Some people see coins as a sign of greed, such as some Communists and Puritans, who sometimes condemn over-hoarding of coins, and ascetics, who often keep little in the ways of money (coins), leading a "poor"-lifestyle.

paragraphs: Because coins have been made for a very long time, some people collect old coins. They can be much cheaper than other old things, especially if they are made of cheap metals like copper. Older coins normally cost more than newer ones, but rarity matters more-some coins from the 1920s cost vast sums, while some Roman coins cost very little.


title: Conceptual metaphor

paragraphs: A conceptual metaphor or cognitive metaphor is a metaphor which refers to one domain (group of ideas) in terms of another. For example, treating quantity in terms of direction:

paragraphs: The idea of a conceptual metaphor came from a book by George Lakoff and Mark Johnson in 1980: "Metaphors we live by".

paragraphs: A convention is to write conceptual metaphors in small capital letters, e.g. , with the target domain (idea being referred to) first, here "money," and the source domain (terms used to refer to it) second.

paragraphs: There are many more, enough to prove the importance of the metaphor in our lives.


title: Crust

paragraphs: Crust is a piece of bread where the edge where it is harder and darker.


title: Comedy

paragraphs: Comedy (from ), in modern times, is entertainment with generally funny content. It is able to make people laugh. This definition was used for theatre plays, and was first used in Ancient Greece. Aristotle defined this as “Comedy is, as an imitation of characters of a lower type- not, however, in the full sense of the word bad, the ludicrous being merely a subdivision of the ugly. It consists in some defect or ugliness which is not painful or destructive. To take an obvious example, the comic mask is ugly and distorted, but does not imply pain.” To him, the lampooners became writers of Comedy and the truly artistic ones became writers of Tragedy.

paragraphs: Comedy is also a media genre that is for television shows or movies that are either funny or silly. People who are known for acting in comedies are termed as comedians or comedic actors.

paragraphs: The ancient Greeks had comedies, which were presented in competitions at the festival of Dionysia.

paragraphs: One of the best-known comedy authors of the time was Aristophanes (about 446386 BC). One of his works, "The Clouds" was performed 425 BC. The work did not survive completely, but a later version did survive. It is a satire against Socrates, and pictures the great philosopher as a swaggering con artist. Some of the accusations were re-used at Socrates' trial, twenty years later.

paragraphs: Typical for satire are that the author criticizes society, and living people.

paragraphs: Another type of Ancient Greek theatre was the satyr play. This was mock drunkenness, brazen sexuality (including phallic props), pranks, sight gags, and general merriment. The modern equivalent would be knock-about comedy.

paragraphs: Humour, or 'New Comedy' is not about criticizing people or ideas, but rather about showing characters in funny situations. The most important Greek playwright of this type was probably Menander. The best known Roman comedy writer was Plautus. He often used Greek comedies for his plays.

paragraphs: Many comedy plays were written in the 1500s by the British writer William Shakespeare.

paragraphs: Shakespeare's comedy plays include:" All’s Well That Ends Well, The Comedy of Errors, A Midsummer Nights Dream", and "Twelfth Night". In Shakespeare's day a comedy did not mean a play that would make people laugh or that had a lot of jokes. Instead it was a play in which all the problems work out all right in the end. This was unlike a tragedy, where the problems do not work out, usually resulting in someone's death.

paragraphs: The two masks, one was smiling, the other crying, often associated with theatre represent comedy and tragedy.

paragraphs: There are different types of comedy. One type of comedy is called "slap stick comedy." In "slap stick comedy," people do silly things such as tripping, falling over or embarrassing themselves just to make people laugh. Slap stick comedy can be used in comedy movies or comedy television shows.

paragraphs: Slap stick comedy was used a lot in silent (no sound) movies from the 1920s. A comedian who acted in the silent movies who used a lot of slapstick comedy was Charlie Chaplin. In the 1950s and 1960s, comedian Jerry Lewis also used silly slap stick comedy in his comedy movies.

paragraphs: A comedy is a very popular type of movie. Some comedy movies have "slapstick comedy," in which people just do silly things such as tripping, falling over or embarrassing themselves just to make people laugh. Other comedy movies show funny stories or situations in which people are behaving in a silly manner. Some comedies make the audience laugh by showing strange or unusual images or situations that do not make sense.

paragraphs: A parody or spoof movie imitates or exaggerates another person or movie to make them seem silly, dumb, or just plain out of it.

paragraphs: Some types of comedy movies mix comedy with other types of movies.

paragraphs: Comedy shows are very popular on television. Comedy shows on television are often called "sitcoms." The word "sitcom" is a shortened way of saying "situational comedy." Television situational comedies usually show characters who do silly or funny things which make the audience laugh.


title: Comet

paragraphs: A comet is a ball of mostly ice that moves around in outer space. Comets are often described as "dirty snowballs". They are very different from asteroids. The orbital inclinations of comets are usually high and not near the ecliptic where most solar system objects are found. Most of them are long-period comets and come from the Kuiper belt. That is very far away from the Sun, but some of them also come near enough to Earth for us to see at night.

paragraphs: They have long "tails", because the Sun melts the ice. A comet's tail does not trail behind it, but points directly away from the Sun, because it is blown by the solar wind.

paragraphs: The hard centre of the comet is the "nucleus". It is one of the blackest things (lowest albedo) in the solar system. When light shone on the nucleus of Halley's Comet, the comet reflected only 4% of the light back to us.

paragraphs: "Periodic" comets visit again and again. "Non-periodic" or "single-apparition" comets visit only once.

paragraphs: Comets sometimes break up, as Comet Biela did in the 19th century. Comet Shoemaker-Levy 9 broke up, and the pieces hit Jupiter in 1994. Some comets orbit (go around) together in groups. Astronomers think these comets are broken pieces that used to be one object.

paragraphs: For thousands of years, people feared comets. They did not know what they were, or where they came from. Some thought that they were fireballs sent from demons or gods to destroy the earth. They said that each time a comet appeared, it would bring bad luck with it. Whenever a comet appeared, a king would die. For example, the Bayeux Tapestry shows the return of Halley's Comet and the death of a king. Comets were also known to end wars and thought to bring famine. During the Renaissance, astronomers started to look at comets with less superstition and to base their science on observations. Tycho Brahe reasoned that comets did not come from the earth, and his measurements and calculations showed that comets must be six times farther than the earth is from the moon.

paragraphs: Edmond Halley reasoned that some comets are periodic, that is, they appear again after a certain number of years, and again and again. This led to the first prediction of a comet's return, Halley's Comet, named after him.

paragraphs: Isaac Newton also studied comets. He realised that comets make U-turns around the sun. He asked his friend Edmond Halley to publish this in his book "Philosophiae Naturalis Principia Mathematica". Before Newton said this, people believed that comets go in to the sun, then another comes out from behind the sun.

paragraphs: In later years some astronomers thought comets were spit out by planets, especially Jupiter.

paragraphs: All this new information and research gave people confidence, but some still thought that comets were messengers from the gods. One 18th century vision said that comets were the places that hell was, where souls would ride, being burned up by the heat of the sun and frozen by the cold of space.

paragraphs: In modern times space probes have visited comets to learn more about them.


title: Cytology

paragraphs: Cytology is the study of the cells, especially their appearance and structure. Cells are the small parts that make up all living things, and their effects on each other and their environment.

paragraphs: There are two types of cells. Prokaryotic cells do not have a clear and easy-to-see nucleus, and do not have a membrane, or wall, around them. Eukaryotic cells have an easy-to-see nucleus where all of the cell's functions take place, and a membrane around them. The main organelles of a cell and their uses are:


title: Christian

paragraphs: A Christian is a person who believes in Christianity, a monotheistic religion. Christianity is mostly about the life and teachings of Jesus Christ, in the New Testament and interpreted of prophesied in the Hebrew Bible/Old Testament. Christianity is the world's largest religion, with 2.1 billion followers around the world.

paragraphs: Christians consider the Holy Bible to be a sacred book, inspired by God. The Holy Bible is a combination of the Hebrew Bible, or Torah, and a collection of writings called the New Testament. Views on the importance of these writings vary. Some Christian groups prefer to favor the New Testament, while others believe the entire Bible is equally important. Also, while many Christians prefer to consider the Bible as fully true, not all Christian groups believe that it is completely accurate.

paragraphs: The question of "who is a Christian?" can be very difficult. Christians often disagree over this due to their differences in opinion on spiritual matters. In countries where most persons were baptized in the state church or the majority Christian church, the term "Christian" is a default label for citizenship or for "people like us".

paragraphs: In this context, religious or ethnic minorities can use "Christians" or "you Christians" as a term for majority members of society who do not belong to their group - even in a very secular (though formerly Christian) society.

paragraphs: Persons who are more devoted the their Christian faith prefer not to use the word so broadly, but only use it to refer to those who are active in their Christian religion and really believe the teachings of Jesus and their church. In some Christian movements (especially Fundamentalism and Evangelicalism), to be a born-again Christian is to undergo a "spiritual rebirth" by believing in the Bible's teachings about Jesus and choosing to follow him.

paragraphs: Many Christians choose to go to church. Most Christians believe this to be a sign of their religious devotion to God and an act of worship. However, some Christian groups think that one can be a Christian without ever going to a church. Though there are many different viewpoints on the issue, most Protestants believe all Christians are part of the spiritual church of Christ, whether or not those Christians go to an actual church each week. On the other hand, Catholics in the past have believed that the Holy Catholic Church is the only true church.


title: Cheese

paragraphs: Cheese is a type of dairy that comes from milk. There are many types of cheese, such as cheddar, Swiss, and provolone.

paragraphs: Many things affect the form, texture, colour and flavour of a cheese. These include the milk (cow or goat), if the milk has been pasteurized, the amount of butterfat, bacteria and mold in the cheese, how the cheese is made, how much fat is in the cheese, and how old the cheese is.

paragraphs: People have been making cheese since before history was written down. It is not known when cheese was first made. It is known that cheese was eaten by the Sumerians in about 4000 BC.

paragraphs: Cheese is made using milk. The milk of cows, goats, and sheep are most popular. Buffalo, camel, donkey and even hippopotamus milk can also be used. Cheese makers usually cook the milk in large pots.

paragraphs: Most cheeses are acidified by bacteria. This bacteria turns milk sugars into lactic acid.

paragraphs: Salt is added, and a substance from the stomach of young cows called rennet. This curdles the cheese and makes it solid. Some makers do not add rennet, but curdle the cheese in other ways. Vegetarian alternatives to rennet are made by fermentation of a fungus called "Mucor miehei". Other alternatives use species of the "Cynara" thistle family.

paragraphs: Other ingredients are added and the cheese is usually aged for a varied length of time.

paragraphs: There are many different ways to classify cheeses. Some ways include:

paragraphs: There are also man-made foods that some people use instead of cheese. These are called Cheese analogues.


title: Constitution

paragraphs: The constitution of a country (or a state) is a special type of law document that tells how its government is supposed to work. It tells how the country's leaders are to be chosen and how long they get to stay in office, how new laws are made and old laws are to be changed or removed based on law, what kind of people are allowed to vote and what other rights they are guaranteed, and how the constitution can be changed.

paragraphs: Limits are put on the Government in how much power they have within the Constitution "(see Rule of Law )". On the other hand, countries with repressive or corrupt governments frequently do not stick to their constitutions, or have bad constitutions without giving freedom to citizens and others. This can be known as dictatorship or simply "bending the rules". A Constitution is often a way of uniting within a Federation.

paragraphs: The UK's constitution is not written in one single document like many other countries' are. In fact, the UK's constitution is not completely written down at all. Some of it can be found in writing, starting with the Magna Carta of 1215 and the Bill of Rights Act 1689 and including more modern Acts of Parliament. Other parts of it are considered common law and are made up of the decisions of judges over many hundreds of years in a system called legal or judicial precedence. Because of this, some people say that the United Kingdom has a "de facto" or "unwritten" constitution.

paragraphs: The United States in 1787 began a trend in the writing of constitutions. The United States Constitution is also the shortest that people are still using, and it has been changed (amended) many times over the years. It was made after the colonists won their independence from Britain. At first they had the Articles of Confederation but the Articles were replaced with today's Constitution.

paragraphs: The Indian constitution of 1950 is the longest ever written constitution in the world. It has 448 Articles and 12 Schedules in it, with 5 appendices and 98 amendments.


title: Circle

paragraphs: A circle is a round, two-dimensional shape. All points on the edge of the circle are at the same distance from the center.

paragraphs: The radius of a circle is a line from the centre of the circle to a point on the side. Mathematicians use the letter "r" for the length of a circle's radius. The centre of a circle is the point in the very middle. It is sometimes written as formula_1.

paragraphs: The diameter (meaning "all the way across") of a circle is a straight line that goes from one side to the opposite and right through the centre of the circle. Mathematicians use the letter "d" for the length of this line. The diameter of a circle is equal to twice its radius ("d" equals 2 times "r"):

paragraphs: The circumference (meaning "all the way around") of a circle is the line that goes around the centre of the circle. Mathematicians use the letter "C" for the length of this line.

paragraphs: The number "π" (written as the Greek letter "pi") is a very useful number. It is the length of the circumference divided by the length of the diameter ("π" equals "C" divided by "d"). As a fraction the number π is equal to about or 335/113 (which is closer) and as a number it is about 3.1415926535.

paragraphs: The area, "A", inside a circle is equal to the radius multiplied by itself, then multiplied by π ("A" equals π times "r" times "r").

paragraphs: π can be measured by drawing a large circle, then measuring its diameter ("d") and circumference ("C"). This is because the circumference of a circle is always π times its diameter.

paragraphs: π can also be calculated by only using mathematical methods. Most methods used for calculating the value of π have desirable mathematical properties. However, they are hard to understand without knowing trigonometry and calculus. However, some methods are quite simple, such as this form of the Gregory-Leibniz series:

paragraphs: While that series is easy to write and calculate, it is not easy to see why it equals π. An easier-to-understand approach is to draw an imaginary circle of radius r centered at the origin. Then any point ("x","y") whose distance d from the origin is less than r, calculated by the Pythagorean theorem, will be inside the circle:

paragraphs: Finding a set of points inside the circle allows the circle's area A to be estimated, for example, by using integer coordinates for a big r. Since the area A of a circle is π times the radius squared, π can be approximated by using the following formula:


title: Capitalization

paragraphs: Capitalise (British spelling) or capitalize (North American spelling) means to make one or more letters upper case. The first letter of a sentence is capitalised in many languages, as are the first letters of proper nouns such as names of people and places. In German, however, all nouns are capitalized. It is the only language to do that.

paragraphs: The homonym capitalize is a different word, and means "to fully fund as an investment".


title: Cuba

paragraphs: Cuba is an island country in the Caribbean Sea. The country is made up of the big island of Cuba, the Isla de la Juventud island ("Isle of Youth"), and many smaller islands. Havana is the capital of Cuba. It is the largest city. The second largest city is Santiago de Cuba. In Spanish, the capital is called "La Habana". Cuba is near the United States, Mexico, Haiti, Jamaica and the Bahamas. People from Cuba are called Cubans ("cubanos" in Spanish). The official language is Spanish. Cuba is warm all year.

paragraphs: In 1492, Christopher Columbus landed on the island of Cuba. He claimed it for the Kingdom of Spain. Cuba became a Spanish colony until the Spanish–American War of 1898. After the war, it was part of the United States. It gained independence in 1902.

paragraphs: In 1959, guerrilla fighters led by Fidel Castro and Che Guevara overthrew Cuba's dictator, Fulgencio Batista, in what became the Cuban Revolution. Castro began making relations with the Soviet Union and tried to close a lot of American businesses in Cuba; the United States did not like this. In 1961 Castro officially announced that his government was socialist. The US attempted to invade Cuba to regain control of it and overthrow it's communist led government but failed. The Communist Party of Cuba was created in 1965 and has ruled the island ever since. Today, Cuba is the only communist state outside of Asia, in the Caribbean, and in the western hemisphere.

paragraphs: Cuba is famous for many types of music, especially dance music such as the Salsa and Mambo. Because Cubans have ancestors from Spain, Africa, South America and North America, Cuban music is special and different.

paragraphs: Reading is very popular in Cuba. Many people especially enjoy reading books or things that come from outside the country, even though the government does not approve of this. They also love music and sports. Cuban music is very lively. This is because a lot of it comes from African and Spanish rhythms. Baseball, basketball, and athletics events are loved by many Cuban people. The Cheifs football-team took at one Football-World-Cup part. In 1938, they reached the quarter-final and lost against Sweden 0:8.

paragraphs: Before Cuba was conquered by the Spaniards, three tribes lived on the island. They were the Taínos, the Ciboneys, and the Guanajatabeyes. The Taínos were the largest and most common of the three tribes. They farmed crops such as beans, corn, squash, and yams. The Taínos also slept in hammocks which the Spaniards would introduce to the rest of the world. Then, in 1492, Christopher Columbus arrived in Cuba on his first trip to the Americas. Three years later he claimed the islands for the Spanish. The Spanish began to rule Cuba afterwards. The Spanish brought thousands of slaves from Africa to Cuba to work for them. Most of the native Cubans died because of the new diseases brought by the Spanish and Africans. The Spanish also treated the native Cubans very cruelly and massacred many of them.

paragraphs: The Spanish ruled for many years. Cuba became the most important producer of sugar. In the early 1800s, Cubans rebelled against the Spanish rulers, but failed until 1898, when the United States went to war with the Spanish and defeated them. Cuba became American for four years afterwards, before it became an independent republic in 1902. Even though Cuba was independent, the Americans still controlled the island by a law called the Platt Amendment. In 1933 the Cubans stopped the Platt Amendment, but the Americans still had a big say in Cuban politics. Americans owned most of Cuba’s businesses. The Americans supported the leader Fulgencio Batista, who was seen by many Cubans as corrupt.

paragraphs: In addition to political control, the United States also exercised significant control over the Cuban economy. At the time, Cuba was a monoculture economy. While they produced coffee, tobacco, and rice, they relied primarily on sugar. Thus, they were known by other countries as the "sugar bowl of the world." The United States bought sugar from the Republic of Cuba at a price higher than the global standard. In exchange, Cuba was to give preference to the United States, and its industries. Cuba depended on the United States and their investments. Cuba was not industrialized and needed the revenue for goods and oil. They also needed the US investment for gas, electricity, communications, railways, and banks. While Cuban workers had better conditions than other countries in the continent, they still faced inequality, lack of infrastructure, high illiteracy rates, and a lack of full-time work (the sugar industry was seasonal).

paragraphs: In 1959, Fidel Castro led a revolution against Fulgencio Batista. Castro took power in Cuba with Che Guevara from Argentina, his brother Raul, and others who fought against Batista. Castro made many changes to Cuba. He ended American ownership of Cuban businesses. This made Castro unpopular in America and the United States banned all contact with Cuba. Many Cubans went to America because of this. In 1961, the Americans helped some of these Cubans to attack Cuba and try to remove Castro, but they failed. Castro then asked the Soviet Union to help defend them from the Americans, which they did. The Soviet Union put nuclear weapons in Cuba and aimed them at the United States. American President Kennedy demanded that they be removed or a new war would begin. This was known as the "Cuban Missile Crisis". The Soviet Union removed the missiles when the United States agreed to not continue attacking Cuba and to remove missiles from Turkey.

paragraphs: Cuba became a communist-led country like the Soviet Union after this. The Soviet Union bought most of Cuba’s sugar for expensive prices. Cuba spent this money on health, education and the army. This made Cuba’s schools and hospitals some of the best in the world. The army fought in Africa to support black Africans against the white South African army. Cuba also supported groups in South America fighting against the dictators of those countries.

paragraphs: However, the Cuban government began to control most of life in Cuba under the communist system. Disagreeing with the Cuban government and Fidel Castro in public was not allowed. Some Cubans did not like this and tried to leave Cuba. Most Cubans who left went to the United States. Some Cubans who did not like the government and stayed were put in jail. Many groups from around the world protested against Cuba because of this, and demanded that Fidel Castro give up power.

paragraphs: In 1991, the Soviet Union collapsed. This meant that Cuba, which had sold most of its products to the Soviet Union, had no money coming into the country. The Americans made the restrictions against contact with Cuba tighter. America said the restrictions on contact would continue unless Fidel Castro gave up power. Cuba became very poor in the 1990s. This became known in Cuba as “The Special Period”. Because of the disaster, Cuba changed to allow less control by the government, more discussion amongst the people, and private shops and businesses. Cuba also tried to get tourists to visit the island.

paragraphs: In the 2000s, tourism to Cuba began to make money for the island again. Though Fidel Castro had remained in power, he had passed all duties to his brother Raul after an illness. Fidel Castro was one of the longest-serving heads of state. In 2018, Miguel Díaz-Canel became the official President of Cuba.

paragraphs: In April 2015, historic talks took place with US President Obama and Cuban General Secretary Raúl Castro in improving relations between the two nations.

paragraphs: The trade embargo issued by President Kennedy in the 1960s has been considerably loosened under Obama's administration. US citizens can now travel directly to Cuba at certain times of the year. Before, Americans had to go via Mexico if they wanted to go to Cuba. Americans are still not allowed to purchase or smoke Cuban cigars. The cigars are smuggled over the US-Canadian border since they are legal in Canada.

paragraphs: For military service, men from the age of 17 to 28 years old must go into the army for two years. It is optional for women.

paragraphs: The country is divided into 15 provinces and one special municipality (Isla de la Juventud). The provinces are divided into municipalities.

paragraphs: The population of Cuba is close to 13 million. The people of Cuba come from three different groups. The largest group is the descendants of the Spanish settlers who came to Cuba. The smallest group is the descendants of the black African slaves who were brought in to do the work and birth children (in the barracoon) as New World slaves who could be legally sold into life time bondage in the United States. The middle-sized group is a mix of African and Spanish. The government succeeded in seeing that the three different groups were treated the same. According to a DNA Caribbean Studies Institute, the racial-makeup of the population of Cuba is:

paragraphs: Cuba is a developing country, and is often depicted as a very poor country. In some aspects, however, like education, health care and life expectancy it ranks much better than most countries in Latin America. Its infant death rate is lower than some developed countries. The average life expectancy is 78 years.

paragraphs: All the children are required to go to school from six to twelve years old, and nearly everybody is able to read and write at least. There is free education at every level. Because of this, Cuba has a 99.8% literacy rate.

paragraphs: In 2006, the World Food Programme certified Cuba to be the only country in this region without undernourished children. In the same year, the United Nations said that Cuba was the only nation in the world that met the World Wide Fund for Nature's definition of sustainable development.

paragraphs: Cuba is the largest island in the West Indies. It has many resources. Only about one-fourth of the land is mountains or hills. Much of the land is gentle hills or plains which are good for farming or raising cattle. Cuba has fertile soil and a mostly warm and humidodity climate that makes it a great place for growing crops.

paragraphs: Sugar is the most important crop of Cuba, and they may get it from the sugar cane. Sugar cane is the largest cash crop grown in Cuba, and it brings in most of the money. After that, the second is tobacco. Tobacco is made into cigars by hand. A hand-made cigar is considered by many people to be the finest in the world. Other important crops are rice, coffee, and fruit. Cuba also has many minerals. Cobalt, nickel, iron, copper, and manganese are all on the island. Salt, petroleum, and natural gas are there too. The coast of Cuba has many bays and a few good harbors. Havana, which is the capital, is also a port. Other harbors have port cities. Nuevitas is a port city on the north coast. Cienfuegos, Guantánamo, and Santiago de Cubaare some of the port cities on the south coast.

paragraphs: Cuba has a semi-tropical climate. That means that the cool ocean winds keep it becoming hot, despite its being in the tropiocal zone. Cuba has a wet season and a dry season. The dry season is from November to April, and the wet season is from May to October. August to October is also the hurricane season in the Atlantic Ocean. Because of this, most of Cuba's port cities can be flooded along the coast.


title: Cube

paragraphs: A cube is a block with all right angles and whose height, width and depth are all the same.

paragraphs: A cube is one of the simplest mathematical shapes in space. Something that is shaped like a cube is sometimes referred to as "cubic".

paragraphs: The basic difference between a cube and a square is, a cube is a 3D figure (having 3 dimensions) i.e. length, breadth and height while a square has only 2 dimensions i.e. length and breadth.

paragraphs: The 2-dimensional (2D) shape (like a circle, square, triangle, etc.) that a cube is made of is squares. The sides (faces) of a cube are squares. The edges are straight lines. The corners (vertices) are at right angles. A cube has 8 corners, 12 edges and 6 faces, as in the most usual kind of dice. A tesseract carries this idea into the fourth dimension (4D) and is made of 8 cubes.


title: Cost of living

paragraphs: Cost of living is the amount of money it costs just to live in a certain place. It includes food, housing, etc.


title: December

paragraphs: December (Dec.) is the twelfth and last month of the year in the Gregorian calendar, with 31 days, coming between November (of the same year) and January (of the following year). With the name of the month coming from the Latin "decem" for "ten", it was the tenth month of the year before January and February were added to the Roman calendar.

paragraphs: December always begins on the same day of the week as September, and ends on the same day of the week as April.

paragraphs: December's flower is the Narcissus. Its birthstone is the turquoise. The meaning of the turquoise is prosperity.

paragraphs: Some of the holidays celebrated in December are Christmas, New Year's Eve, Kwanzaa, and Hanukkah.

paragraphs: December is the 12th and last month of every calendar year in the Gregorian calendar, and is one of seven months of the year to have 31 days. December 31 is followed by January 1 of the following year.

paragraphs: December begins on the same day of the week as September every year, as each other's first days are exactly 13 weeks (91 days) apart. December ends on the same day of the week as April every year, as each other's last days are exactly 35 weeks (245 days) apart.

paragraphs: In common years, December starts on the same day of the week as April and July of the previous year, and in leap years, October of the previous year. In common years, December finishes on the same day of the week as July of the previous year, and in leap years, February and October of the previous year. In leap years and years immediately after that, December both starts and finishes on the same day of the week as January of the previous year.

paragraphs: In years immediately before common years, December starts on the same day of the week as June of the following year, and in years immediately before leap years, March and November of the following year. In years immediately before common years, December finishes on the same day of the week as September of the following year, and in years immediately before leap years, March and June of the following year.

paragraphs: December is one of two months to have a solstice (the other is June, its seasonal equivalent in both hemispheres), and in this month the Tropic of Capricorn in the Southern Hemisphere is turned towards the Sun, meaning that December 21 or December 22 is the Northern Winter Solstice and the Southern Summer Solstice. This means that this date would have the least daylight of any day in the Northern Hemisphere, and the most in the Southern Hemisphere. There are 24 hours of darkness at the North Pole and 24 hours of daylight at the South Pole.

paragraphs: In mainly Christian countries, December is dominated by Christmas, which is celebrated on December 25 in most of those countries, though Eastern Orthodox Christians celebrate it on January 7. It marks the birth of Jesus Christ. Epiphany, January 6, is also important in relation to Christmas. Advent starts on the Sunday on, or closest to, November 30, and some countries have their own related celebration before the 25th. Sinterklaas is celebrated on December 5 in the Netherlands and Belgium, and St. Nicholas Day on December 6 is also celebrated in some countries. The Scandinavian countries, mainly Sweden, celebrate St. Lucia Day on December 13, while Iceland celebrates Thorlaksmessa on December 23. The week after Christmas is spent preparing for New Year.

paragraphs: Judaism's festival of light, Hanukkah, is also celebrated over eight days in this month.


title: Dublin

paragraphs: Dublin () is the capital of the Republic of Ireland, and the biggest city on the island of Ireland. In 2011 there were over 1.1 million people living in the Greater Dublin Area.

paragraphs: Dublin was built by the Vikings upon the river Liffey. The river divides the city into two parts, North Dublin and South Dublin.

paragraphs: Many famous writers lived in Dublin. Oscar Wilde and George Bernard Shaw were born in Dublin. James Joyce is probably Dublin's best known and most international writer.

paragraphs: Dublin is home to Ireland's largest stadium for all sports, Croke Park. It can hold up to 85,000 people. Croke Park is the usual venue for all Ireland hurling and football finals. The Aviva Stadium hosts rugby and soccer.


title: Dance

paragraphs: Dance is a performing art. It is described in many ways. It is when people move to a musical rhythm. They may be alone, or in a group. The dance may be an informal play, a part of a ritual, or a part of a professional performance. There are many kinds of dances, and every human society has its own dances.

paragraphs: As with other performing arts, some people dance to express their feelings and emotions, or to feel better. Dance can be used to tell a story. In some societies, dance goes with song as well as music. Dancing is sometimes done as sport, and has similar athletic aspects. People who want to learn to dance can go to dance schools. It may take years of practice to become an experienced and capable dancer.

paragraphs: To plan a dance is called "choreography", done by a choreographer. Often this goes with music, and fits into a certain style. Dances may be planned in detail, or they may be whatever dancers feel like doing. However, most dancing does follow some general style or pattern. One style is the couple dance, where (usually) a man and a woman dance together. Other dances need an ensemble, a group of people together to make it work.

paragraphs: People have always danced. Every society has its own dances. There are pictures, on pottery and stone, which show dances from several thousand years ago, in Egypt and Greece.

paragraphs: Sachs divides early dances into 'Imageless dances' and 'Image dances'. By 'imageless dances' he meant dances which have no set form, but aim at getting the dancers into a state of ecstasy. In this state the dancer(s) seem changed, in a trance, and are often thought of (by their society) as being 'possessed by spirits'. These dances are done on certain occasions: marriage, war, famine, illness or death, and so on. They are found in all early ('primitive') societies.

paragraphs: The 'image dances', according to Sachs, are to do with the world outside the dancer. By imitating an animal or object, the dancer believes he can capture a power and make it useful. To dance in imitation of the animal which is going to be hunted is to become one with them. To imitate the act of sex is to achieve fertility. This is the kind of thinking behind an image dance. Sachs points out that societies of this kind do not really understand the connection between cause and effect. They really believe the image dances work. The dance type which is used in image dances is mime.

paragraphs: The two styles of dance may be joined together. Fertility dances may involve both ecstatic states and mime. The great dancer Nijinsky used some of these ideas in his choreography for the ballet "Le Sacre du Printemps" (The Rite of Spring), a ballet about the sacrifice of a girl during a primitive celebration of Spring.

paragraphs: In more recent times, the first dance school we know about was opened in 1661 in Paris. Only men were accepted until 1681. After 1681, women were accepted too. Ballroom dances are forms of modern dance. Ballroom dances such as the waltz are done by couples.

paragraphs: Until the 20th century, most ballroom dances were sequence dances. The way people moved was planned in set formation. These formations were usually lines or squares. Everyone moved at the same time, and finished at the same time. The music played for a set time, and then stopped. After the invention of the waltz, around 1800, another style of dancing developed. In the waltz, and later dances, people danced in couples, but they did so separately. They did not dance in formation, but moved round the room as they pleased (but anti-clockwise). Often, new dance styles arrive. Some dance as individuals, separately, as they please. Street dance is like that. All these types of dance have music.

paragraphs: At the same time, round the world there are many traditional dances. Some of them have been going for hundreds of years. We call them folkloric dances.

paragraphs: The coming of popular music videos and DVDs led to a kind of dancer previously seen in some stage shows. A backup dancer (or background dancer) is a performer who dances with or behind the lead performers in a live musical act or in a music video.

paragraphs: There are many different styles of dance, which fall into these general types:


title: Dissolution of the monasteries

paragraphs: The dissolution of the monasteries was an event that happened from 1536 to 1540, when English King Henry VIII took away the land and money that the nuns and monks of the Roman Catholic church owned. Henry VIII then gave this land and money to people that supported him.

paragraphs: This was also when Henry VIII made himself the new head of the Church of England (which is a type of Christianity). Parliament made the Act of Supremacy to give him the right to do both these things. It was part of the Protestant Reformation in England.


title: Deadline

paragraphs: A deadline is a time by which some task must be completed.

paragraphs: Very often, it means a time limit that is set in place by an authority - for example, a teacher tells students that they must turn in their homework in by a certain time. This is so the teacher is able to report fairly to his or her principal that every student had the same chance to do the work.

paragraphs: Deadlines may also be set by a time horizon that comes from something that is not a human authority, but part of nature. For example, by sunset one must do those tasks requiring daylight. However, a human must watch the sun and decide what light is strong enough to still be daylight, so time limits will still be involved even if one observes a horizon and sets a deadline oneself.

paragraphs: A way to remember this is that a time horizon is like the physical horizon where sunset happens and a time limit is a thing people set up to deal with this. A deadline is a thing powerful people set up to ensure less powerful people comply with their way of doing things.


title: Dutton's Speedwords

paragraphs: Dutton Speedwords is a made-up language written by Reginald John Garfield Dutton. The idea of Dutton Speedwords is to make frequent words short, and very frequent words very short. Dutton Speedwords can be used as a second language for international communications. Dutton Speedwords is also a shorthand writing system – this means you can use it to write quickly.

paragraphs: The method was made up by Reginald John Garfield Dutton (1886-1970) in 1922. It was first published in 1935. It was called "International Symbolic Script". A year later, it was called "Speedwords". It was changed in 1946 and 1951.

paragraphs: It has two uses; to be a language and to be used for writing quickly. Dutton hoped that this would mean more people would learn it because they could use it for two reasons.

paragraphs: The books that Dutton wrote about Speedwords are not printed anymore. But Speedwords is now being used by more people because they find it is good for working online. For example, it makes it faster to type an email.

paragraphs: Another way of writing quickly is Pitman's shorthand. This uses special symbols instead of letters. Speedwords uses Roman letters. This makes it easier to learn. It also means it can be typed using a normal keyboard. Each word means only one thing. This means you do not need to use different forms of the same word.

paragraphs: The words used in Speedwords are the same as the words used in many other languages. The words are like short versions of the writer's own language.


title: Devil

paragraphs: In some religions, the devil is a bad spirit or supernatural being that tries to create problems for people and distance them from God. Some people also use the words "the Devil" or "Satan" for the most powerful devil. The word "devil" comes from the Greek word "diabolos" which means "someone who tells lies to hurt you". ("Diabolos" is translated to the English word "slanderer.") The New Testament uses "diabolos" as a title for Satan, and so "The Devil" became another name for Satan in English.

paragraphs: In the Old Testament, there is the serpent and the shaitan, who may be two different characters. "Shaitan" in Hebrew means "adversary", an enemy or opponent. Shaitan is also the word used for the devil in the Koran, who often appears as an animal and tries to get people to do the wrong thing.

paragraphs: In Christianity the Devil was originally an angel in heaven called Lucifer. But he refused to love the humans as much as his father, God, as he was instructed, and so he revolted against Heaven. After a hard fight he was defeated and thrown out of heaven. Some other angels who helped him were also thrown out.

paragraphs: After the Devil was thrown out of heaven, he started doing bad things on the earth. He wants people to worship him instead of God. Sometimes he tries to trick people by giving them false promises.

paragraphs: The other angels who were thrown out of heaven became evil spirits called demons. They obey the Devil and help him do evil things.

paragraphs: The Book of Revelation says that God will punish the Devil and his demons by throwing them into a Lake of Fire that burns in Hell. This will happen in the future.

paragraphs: Artists draw pictures of the Devil that show him as ugly and evil. But nobody knows what he may look like. Usually he is a spirit that nobody can see, but he can make himself look like a real person in order to trick people. Many modern depictions of the devil portray him as a red human-like being with horns and a pointed tail, carrying a red pitchfork or trident.

paragraphs: Not all religions believe in the devil. For example, some forms of Buddhism do not believe in the devil. In Wicca, the concept of the Devil and demons is also rejected, simply because, in Wiccan tradition, the creative energy is neither positive nor negative. According to Wiccans: "We are the ones who use this energy for good or evil. Therefore, the consequence of this action is our entire responsibility, not of an evil supernatural being." The corniferous god "Cernunnos" of Wicca was confused with the Christian Devil, for having horns (in antiquity, given the horns were phallic, they were associated with virility (fertility)), and were soon symbols of ancient European religions. He was already worshipped by pagan religions before Christianity arrived in Europe and the British Isles. Many satanists believe in the devil or Satan only as a metaphor, not an actual being or person. In the Bahá'í Faith, the devil as a malevolent, supernatural entity is not believed to exist. These terms do, however, appear in the Bahá'í writings, where they are instead used as metaphors for the lower nature of man.


title: Diarrhea

paragraphs: Diarrhea (DIE-uh-REE-uh), also spelled diarrhoea, happens when the body makes more watery feces than normal. Diarrhea can occur in humans as well as most other mammals.

paragraphs: Diarrhea is not a disease. But it may be a symptom of a disease. The most common causes of diarrhea are:

paragraphs: In developing nations, diarrheal diseases are the second most common cause of death in children under age 5. Every year in the world, diarrhea kills around 760,000 children under age 5.

paragraphs: In developing countries, diarrhea is also one of the most common causes of malnutrition in children under age 5.

paragraphs: When children die from diarrhea, the cause is often dehydration (losing too much water from the body). Because diarrhea is watery, it takes away a lot of the water. It also takes away electrolytes—important salts that the body needs to survive. Dehydration is extra dangerous for small children because they have less water in their bodies to begin with. This means they cannot lose as much water as adults before they start to have serious health problems.

paragraphs: In developing countries, diarrhea is usually caused by an infection in the intestines. These infections can be caused by bacteria, viruses, or parasites. These infections spread easily in some developing countries because of the following reasons:

paragraphs: Child deaths from diarrhea can be prevented in different ways.

paragraphs: When a child is sick with diarrhea, the best way to keep them from dying is to rehydrate them (give them the water and electrolytes (salts) they are losing by having diarrhea). If the child can go to a clinic or hospital, this can be done by giving water and salts intravenously (through a needle placed into a vein).

paragraphs: If the child cannot go to a clinic or hospital, oral rehydration solution can be used. ("Oral" means "given by mouth"; a "solution" is a mixture.) Oral rehydration solution is a mixture of the most important things the body loses when it is dehydrated. These things are clean water, salt, and sugar. Some oral rehydration solutions have extra electrolytes, like potassium, in them also.

paragraphs: Some oral rehydration solutions come in packets and just need to be mixed with clean water. Oral rehydration solution can also be made at home. If the water in the area is not safe, it can be boiled to make it safe. (Boiling the water will kill any bacteria, viruses, or parasites in the water.) Salt and sugar are then mixed into the water. Drinking this mixture, after the water cools, will re-hydrate the child, if he drinks enough. Adding a banana or orange juice can add potassium to the mixture.

paragraphs: Breast milk will also re-hydrate a child with diarrhea.

paragraphs: There are some ways to prevent diarrhea, or the spread of diseases that cause diarrhea. However, some of these ways are expensive and difficult to do. These include:


title: Dimension

paragraphs: Dimensions are the way we see, measure and experience our world, by using up and down, right to left, back to front, hot and cold, how heavy and how long, as well as more advanced concepts from mathematics and physics. One way to define a dimension is to look at the degrees of freedom, or the way an object can move in a specific space. There are different concepts or ways where the term dimension is used, and there are also different definitions. There is no definition that can satisfy all concepts.

paragraphs: In a vector space formula_1 (with vectors being "arrows" with directions), the dimension of formula_1, also written as formula_3, is equal to the cardinality (or number of vectors) of a basis of formula_1 (a set which indicates how many unique directions formula_1 actually has). It is also equal to the number of the largest group of straight line directions of that space. "Normal" objects in everyday life are specified by three dimensions, which are usually called length, width and depth. Mathematicians call this concept Euclidean space.

paragraphs: Dimensions can be used to measure position too. The distance to a position from a starting place can be measured in the length, width and height directions. These distances are a measure of the position.

paragraphs: In some occasions, a fourth (4D) dimension, time, is used to show the position of an event in time and space.

paragraphs: In modern science, people use other dimensions. Dimensions like temperature and weight can be used to show the position of something in less simple spaces. Scientist study those dimension with dimensional analysis.

paragraphs: Mathematicians also use dimensions. In mathematics, dimensions are more general. Dimensions in mathematics might not measure things in the world. The rules for doing arithmetic with dimensions in mathematics might be different than usual arithmetic rules.

paragraphs: Vectors are used to show distances and directions. Vectors are often used in engineering and science, and sometimes in mathematics.

paragraphs: A vector is a list of numbers. There is one number for each dimension. There are arithmetic rules for vectors.

paragraphs: For example, if Jane wants to know the position of Sally, Sally can give Jane a vector to show the position. If Jane and Sally are in the world, there are three dimensions. Therefore, Sally gives Jane a list of three numbers to show her position. The three numbers in the vector Sally gives Jane might be:


title: Distance

paragraphs: Distance is how far one thing is from another thing. It is also a measure of the space between two things. It can be measured along any path. Thus, someone who goes around in a circle has traveled a distance, even though his position has not changed.

paragraphs: In geometry, the distance between two points "A" and "B" is sometimes written as formula_1. Pythagorean theorem is often used in the calculation of distance. Distance is a scalar, and thus is different from displacement. Displacement is a vector that measures distance with a straight line (and in only one path). Displacement is the shortest way to travel the distance.


title: Depth

paragraphs: In math, the distance between the nearest end and farthest end of an object is its depth.

paragraphs: For example, Jane measures a box. When she measures the distance between the end of the box closest to her and the end of the box farthest away, Jane measures the box's depth.

paragraphs: For liquids, the distance between the top or surface of the liquid and the bottom of the liquid is the liquid's depth.

paragraphs: For example, water is a liquid. If you fill a container with water, the distance between the top of the water and the bottom of the container is the water's depth. If the depth is big we say the water is deep.


title: Dictionary

paragraphs: A dictionary is a type of book which explains the meanings of words or, more precisely, lexemes. The words are arranged in alphabetical order so that they can be found quickly. The word "dictionary" comes from the Latin "dictio" ("saying").

paragraphs: There are several types of dictionaries: dictionaries which explain words and how they are used, dictionaries which translate words from one language to another, dictionaries of biography which tell about famous people, technical dictionaries which explain the meanings of technical words or words connected to a particular subject (sometimes called a thesaurus). Some of these come close to being an encyclopedia, but an encyclopedia gives a lot of extra information about things (knowledge) and does not explain the use of the language. An encyclopedic dictionary gives less information about the topic than a real encyclopedia does, but more than a simple dictionary.

paragraphs: Dictionaries which explain what words mean will give a clear "definition" of the word (e.g. hippopotamus : a hoofed mammal with thick skin, large mouth and short legs that lives in rivers and lakes of Africa.)

paragraphs: A big dictionary will also give more information about the word. It will explain how it is pronounced. Usually the International Phonetic Alphabet is used for this. It will explain how the word is used. This is not a problem for a word like "hippopotamus", but a word like "put" has so many different meanings that a large dictionary may have a whole page or more to explain how it can be used. It will also explain the origin of the word (e.g. Greek "hippos" horse and "potamus" river).

paragraphs: A dictionary may also give the form of the word in different tenses, plural form etc.

paragraphs: There are also dictionaries which translate words into foreign languages. Often one volume (one book) will translate both ways; for example, half the book might be translating from English to Dutch and the other half from Dutch to English.

paragraphs: When using a dictionary to find out how to say something in another language one has to be careful to choose the right word. A word like "right" has two basic meanings in English: 1) "correct", and 2) the opposite of "left". Other languages have different words for these different meanings, but they have homonyms of their own. A word like "put" has many meanings. A good dictionary will have a large list of these meanings to help people find the word they want. In many languages, for example, the word “put” will be different according to whether something is being put onto something (e.g. a table) or into something (e.g. a cupboard).

paragraphs: Dictionaries need to be updated frequently because of the way language changes. New words are often brought into a language (e.g. lots of computer terms) or words change their meanings (e.g. "gay" or "cool"). In this sense, the most famous English Dictionary is the Oxford English Dictionary (or OED). Words are always being added to the OED. They are never taken out even if they are obsolete (not used any more). The OED can be accessed online (with a subscription).


title: Definition

paragraphs: A definition is an exact word or phrase of the meaning, nature, or limits of something. A definition usually answers the question "what". "Defining" means giving a definition. Other words with this meaning are "description" and "explanation". It describes what a word means and explains to the person when and where it can be used.

paragraphs: In mathematics, a definition is an exact way of saying what something is. It might not be the easiest way to say what it is, but it is used because it is exact. It can be used in a mathematical proof about the thing.