title: French language

paragraphs: French (French: "", pronounced "Fronce-eh") is a Romance language that was first spoken in France. It is also spoken in Belgium (Wallonia), Luxembourg, Quebec (Canada), Switzerland (Romandy) and many different countries in Africa (Francophone Africa). About 220 million people speak French as a native or a second language. It has also been one of the roots of other languages such as the Haitian Creole language. Like the other Romance languages, its nouns have genders that are divided into masculine ("masculin") and feminine ("féminin") words.

paragraphs: In ancient times, the Celts lived in what is now France. In those days, the land was called Gaul (Latin: Gallia). The Romans conquered Gallia and divided it into provinces. Because the Romans spoke Latin, the local people learned Latin and began to speak it. Their own language, Gaulish, tended to be spoken less often, although Breton is a language still spoken today in the part of France called Brittany, that came from the old Celtic language.

paragraphs: French pronunciation, more so than other Romance languages, became radically different from Latin. After the Roman Empire fell and Germanic peoples swarmed the countryside, Vulgar Latin was changing quickly. In medieval France it changed into two dialects or languages: "langue d'oc" and "langue d'oïl". They both mean "language of yes", because "oc" was the word for "yes" in the south, and "oïl" meant "yes" in the north. Today, the word for yes in French is "oui", pronounced like "we".

paragraphs: In 1635, France established the French Academy in order to standardize the French language. To this day, the academy establishes the rules for Standard French.

paragraphs: "Langue d'oc" is now called Occitan, and it is still spoken by many people in Southern France.

paragraphs: French uses the roman alphabet, like English. There are a few differences, because vowels can have three types of diacritics added on to them. These are the acute accent é; grave accent è and circumflex accent î. A cedilla can also be added onto a c to make ç.

paragraphs: If a word ends with a consonant, this will usually not be pronounced unless the next word starts with a vowel. However, if the word is very short or the last consonant is a c, r, l or f, this is still pronounced.

paragraphs: Here are some examples of French words and sentences :

paragraphs: Many French words are like English words, because English took many words from the Norman language, a dialect of French influenced by Old Norse. This is despite the fact that scholars consider English to be a Germanic language like German. Words in different languages with the same meaning which are spelled similarly are called cognates. Most English words ending with "tion" and "sion" came from the French language. See below for more examples:


title: Prime minister

paragraphs: A prime minister manages the politics of a country and is the head of government. With countries that have kings and queens (known as monarchs), they are very important because they are in charge of most of the politics (they are "head of the government"). In countries with a president, they might be in charge of most of the politics (as in the Republic of Ireland), or they may be in day-to day charge, but taking orders from the president as in France.


title: Greenland

paragraphs: Greenland is the world's largest island.

paragraphs: Greenland is a semi-autonomous territory of the kingdom of Denmark. This large Arctic island is near Iceland to the east and Canada to the west. It has a population of only 50,000 people, limited by its cold climate. Most of the civilian population lives in the southern part of the island, on the coasts. The capital of Greenland is Nuuk.

paragraphs: The island is democratic, with its own elections and a representative seat of government in Nuuk. It is part of the Kingdom of Denmark, a constitutional monarchy with Queen Margrethe II as head of state.

paragraphs: The island's Thule Air Base is under Danish control, but is administered by the United States Air Force.

paragraphs: The island is the least densely populated country in the world, with a density of 0.026 people per square kilometer. Antarctica is not counted because it is not an independent country and has no permanent inhabitants.

paragraphs: The ice sheet that covers Greenland may hide three separate islands, which have been joined by glaciers since the last geologic ice age.

paragraphs: In Greenland, there are no forests. In the south, at the coastal area, only some dwarf trees are found.

paragraphs: Greenland has been inhabited at intervals over at least the last 4,500 years by Arctic peoples. They came from what is now Canada. Norsemen settled the uninhabited southern part of Greenland beginning in the 10th century, having previously settled Iceland.

paragraphs: Norsemen would later set sail from Greenland and Iceland with Leif Erikson. They were the first known Europeans to reach North America. They did so nearly 500 years before Columbus reached the Caribbean islands. Inuit peoples arrived in Greenland in the 13th century. Though under continuous influence of Norway and Norwegians, Greenland was not formally under the Norwegian crown until 1261. Their colonies declined after the Black Death in the late 1400s. Denmark–Norway, joined in alliance at the time, reclaimed sovereignty over the island in the 17th century. Greenland became Danish in 1814.

paragraphs: The island is populated mostly by Inuit and Scandinavians who speak Greenlandic, an Eskimo-Aleut language. Danish is also spoken by most people. The national anthem of Greenland is Nunarput utoqqarsuanngoravit. Greenlandic became the sole official language in June 2009. However, it is the dialect of western Greenland, leaving other dialects to become less used and endangered. Danish is used in practice by professional people and by many of the Inuit population. English is taught in schools from the first year onwards.

paragraphs: Until 2009, there were 20 communes in Greenland. Unless stated otherwise, they are in the district Kitaa:

paragraphs: This changed on January 1st, 2009, when these were merged into four large communes:

paragraphs: In addition, some parts of Greenland are outside a commune, namely:

paragraphs: As of January 1st, 2008, 218 people lived there.

paragraphs: The island has many mountains. All of the cities are on the coast, because everywhere else is covered by a big layer of ice. The major cities are Nuuk, Sisimiut, Ilulissat, and Qaqortoq.


title: Soviet Union

paragraphs: The Soviet Union (short for the Union of Soviet Socialist Republics or USSR) was a single-party Marxist–Leninist state. It existed for 69 years, from 1922 until 1991. It was the first country to declare itself socialist and build towards a communist society. It was a union of 14 Soviet socialist republics and one Soviet federative socialist republic (Russia).

paragraphs: The Soviet Union was created about five years after the Russian Revolution. It was announced after Vladimir Lenin overthrew Alexander Kerensky as Russian leader. The communist government developed industry and over time became a major, powerful union. The largest country in the Union was Russia, and Kazakhstan was the second. The capital city of the Soviet Union was Moscow. The Soviet Union expanded its political control greatly after World War II. It took over the whole of Eastern Europe. Those countries were not made part of the Soviet Union, but they were controlled by the Soviet Union indirectly. These countries, like Poland, Czechoslovakia, and East Germany, were called satellite states.

paragraphs: The top-level committee which made the laws was the Supreme Soviet of the Soviet Union. In practice, the General Secretary of the Communist Party of the Soviet Union was the leader and most important decision-maker in their system of government.

paragraphs: Although the constitution said the Republics could leave the Union if they wanted, in practice it was a completely centralized government, with no states' rights for the member countries.

paragraphs: The Union was formed with the professed idea to give everyone equal social and economic rights. There was virtually no private property—everything belonged to the state. 'Soviets', or workers' councils, were created by the working class to lead the socialist state democratically, but they soon lost power with the rise of Stalinism. The Union was successful in many fields, putting the first man and satellite into space and winning World War II alongside the United States and United Kingdom. However, its centralized government found innovation and change difficult to handle. The Union collapsed in 1991, partly due to the efforts at reform by its leader, Mikhail Gorbachev.

paragraphs: Since 2013, the document that confirmed the dissolution of the Soviet Union has been missing.

paragraphs: The Soviet Union was made of 15 republics. These were either "Soviet Socialist Republics", or "Soviet Socialist Federal Republics". Each republic was independent and handled its own cultural affairs. Each also had the right to leave the union, which they did in 1991.

paragraphs: The "Federal Republics" were different in that they had more autonomy, and were made up of states themselves. These were often called "Autonomous Soviet Socialist Republics". There were a number of them. Most of them still exist; though they are now republics, within the independent state. The "Tatar ASSR" turned into the "Republic of Tatarstan", for example (It is located around Kazan).

paragraphs: The Soviet Union at its largest size in 1991, with , was the world's biggest country. Covering a sixth of the world's lived in land, its size was comparable to North America's. The western part (in Europe) accounted for a quarter of the country's area, and was the country's cultural and economic center. The eastern part (in Asia) extended to the Pacific Ocean to the east and Afghanistan to the south, and was much less lived in than the western part. It was over across (11 time zones) and almost north to south. Its five climatic (different weather, temperature, humidity and atmospheric pressure) zones were tundra, taiga, steppes, desert, and mountains.

paragraphs: The Soviet Union had the world's longest border, measuring over in 1991. Two thirds of the Soviet border was coastline of the Arctic Ocean. Across the Bering Strait was the United States. The Soviet Union bordered Afghanistan, China, Czechoslovakia, Finland, Hungary, Iran, Mongolia, North Korea, Norway, Poland, Romania, and Turkey at the end of WWII.

paragraphs: The Soviet Union's longest river was the Irtysh. The Soviet Union's highest mountain was Communism Peak (today it is called the Ismail Samani Peak) in Tajikistan measured at . The world's largest lake, the Caspian Sea, was mostly in the Soviet Union. The world's deepest lake, Lake Baikal, was in the Soviet Union.

paragraphs: The last Russian Tsar (emperor), Nicholas II, ruled Russia until March 1917, when the Russian Empire was taken over and a short-lived "provisional government" replaced it, led by Alexander Kerensky and soon to be overthrown in November by Bolsheviks.

paragraphs: From 1917 to 1922, the country that came before the Soviet Union was the Russian Soviet Federative Socialist Republic (RSFSR), which was its own country, as were other Soviet republics at the time. The Soviet Union was officially created in December 1922 as the union of the Russian (also known as Bolshevist Russia), Ukrainian, Belarusian, and Transcaucasian Soviet republics ruled by the communist Bolshevik parties.

paragraphs: Extreme government-changing activity in the Russian Empire began with the Decembrist Revolt of 1825, and although serfdom was removed in 1861, its removal was achieved on terms unfavorable to the peasants (poor agricultural workers) and served to encourage changers (revolutionaries). A parliament (legislative assembly)—the State Duma—was created in 1906 after the Russian Revolution of 1905, but the Tsar protested people trying to move from absolute to constitutional monarchy. Rebellion continued and was aggravated during World War I by failure and food shortages in popular cities.

paragraphs: A rebellion in Saint Petersburg, in response to the wartime decay of Russia's economy and morale, caused the "February Revolution" and the removal of the government in March 1917. The tsarist autocracy was replaced by the Russian "Provisional government", whose leaders intended to have elections to Russian Constituent Assembly and to continue war on the side of the Entente in World War I.

paragraphs: At the same time, workers' councils, known as Soviets, sprang up across the country. The Bolsheviks, led by Vladimir Lenin, pushed for socialist revolution in the Soviets and on the streets. In November 1917, during the "October Revolution", they took power from the Provisional Government. In December, the Bolsheviks signed an armistice (peace) with the Central Powers. In March, after more fighting, the Soviets quit the war for good and signed the Treaty of Brest-Litovsk.

paragraphs: In the long and bloody Russian Civil War the new Soviet power won. The civil war between the Reds and the Whites started in 1917 and ended in 1923. It included the Siberian Intervention and other foreign interference, the killing of Nicholas II and his family and the famine in 1921, which killed about 5 million. In March 1921, during a related conflict with Poland, the Peace of Riga was signed and split disputed territories in Belarus and Ukraine between the Republic of Poland and Soviet Russia. The Soviet Union had to resolve similar conflicts with the newly established Republic of Finland, the Republic of Estonia, the Republic of Latvia, and the Republic of Lithuania which had all escaped the empire during the civil war.

paragraphs: On 28 December 1922, people from the Russian SFSR, the Transcaucasian SFSR, the Ukrainian SSR and the Byelorussian SSR approved the Treaty of Creation of the USSR and the Declaration of the Creation of the USSR, creating the Union of Soviet Socialist Republics. These two documents were made true by the 1st Congress of Soviets of the USSR and signed by heads of delegations.

paragraphs: On 1 February 1924, the USSR was accepted as a country by the British Empire. Also in 1924, a Soviet Constitution (set of laws) was approved, making true the December 1922 union of the Russian SFSR, the Ukrainian SSR, the Belarusian SSR, and the Transcaucasian SFSR to form the "Union of Soviet Socialist Republics" (USSR).

paragraphs: The big changes of the economy, industry and politics of the country began in the early days of Soviet power in 1917. A large part of this was performed according to Bolshevik Initial Decrees, documents of the Soviet government, signed by Vladimir Lenin. One of the most important and notable breakthroughs was the GOELRO plan, that planned a major change of the Soviet economy based on total electrification of the country. The Plan was developed in 1920 and covered a 10- to 15-year period. It included the making of a network of 30 regional power stations, including ten large hydroelectric power plants, and numerous electric-powered large industrial organizations. The Plan became the prototype for subsequent Five-Year Plans and was basically fulfilled by 1931.

paragraphs: From its beginning years, government in the Soviet Union was ruled as a one-party state by the Communist Party (Bolsheviks). After the economic policy of War Communism during the Civil War, the Soviet government permitted some private enterprise to coexist with nationalized industry in the 1920s and total food requisition in the countryside was replaced by a food tax ("see" New Economic Policy).

paragraphs: Soviet leaders argued that one-party rule was necessary because it ensured that 'capitalist exploitation' would not return to the Soviet Union and that the principles of Democratic Centralism would represent the people's will. Debate over the future of the economy provided the background for Soviet leaders to take more power in the years after Lenin's death in 1924. Initially, Lenin was to be replaced by a "troika" composed of Grigory Zinoviev of Ukraine, Lev Kamenev of Moscow, and Joseph Stalin of Georgia.

paragraphs: Stalin led the country through World War II and into the Cold War. Gulag camps greatly expanded to take millions of prisoners. After he died, Georgy Malenkov, continued his policies. Nikita Khrushchev reversed some of Stalin's policies but Leonid Brezhnev and Alexei Kosygin kept things as they were.

paragraphs: After the 1936 revised constitution, the Soviet Union stopped acting as a union of republics and more as a single super-country.

paragraphs: Stalin died on 5 March 1953. Nikita Khrushchev eventually won the following power struggle by the mid-1950s. In 1956 he denounced Stalin's repression and eased controls over party and society. This was known as de-Stalinization.

paragraphs: Moscow considered Eastern Europe to be a very vital buffer zone for the forward defense of its western borders. For this reason, the USSR sought to strengthen its control of the region. It did this by transforming the Eastern European countries into satellite states, dependent upon and obedient to its leadership. Soviet military force was used to suppress anti-Stalinist uprisings in Hungary and Poland in 1956.

paragraphs: In the late 1950s, a confrontation with China regarding the USSR's policies led to the Sino–Soviet split. This resulted in a break throughout the global Marxist–Leninist movement. The governments in Albania, Cambodia and Somalia chose to ally with China instead of the USSR.

paragraphs: During this period of the late 1950s and early 1960s, the Soviet Union continued to make progress in the Space Race. It rivalled the United States. The USSR launched the first artificial satellite, Sputnik 1 in 1957; a living dog named Laika in 1957; the first human being, Yuri Gagarin in 1961; the first woman in space, Valentina Tereshkova in 1963; Alexei Leonov, the first person to walk in space in 1965; the first soft landing on the Moon by spacecraft Luna 9 in 1966; and the first Moon rovers, Lunokhod 1 and Lunokhod 2.

paragraphs: Leonid Brezhnev led the Soviet Union from 1964 until his death in 1982. He came to power after he convinced the government to overthrow the then-leader Nikita Krushchev. Brezhnev's rule is often linked with the decline in Soviet economy and starting the chain of events that would lead to the union's eventual collapse. He had many self-awarded medals. He was awarded Hero of the Soviet Union (the highest honor) on three separate occasions. Brezhnev was succeeded by Yuri Andropov, who died a few years later. Andropov was succeeded by the frail and aging Konstantin Chernenko. Chernenko died a mere year after taking office.

paragraphs: In 1980 the Soviet Union hosted the Summer Olympics with Brezhnev opening and closing the games. The games were heavily boycotted by the western nations, particularly the United States. During the closing ceremony, the flag of the City of Los Angeles was raised instead of the flag of the United States (to symbolise the next host city/nation) and the anthem of the Olympics was played instead of the anthem of the United States in response to the boycott.

paragraphs: Brezhnev was the second longest serving Soviet leader after Stalin. The Following is a list of leaders (General Secretary of the Communist Party) in order of their tenure and length of leadership:

paragraphs: Khrushchev and Gorbachev are the only Soviet leaders to have not died whilst in office. Lenin, Stalin and Khrushchev are the only leaders who were not (de jure) head of state during their leaderships.

paragraphs: Mikhail Gorbachev was the Soviet Union's last leader. He was the only Soviet leader to have been born after the October revolution and was thus a product of the Soviet Union having grown up in it. He and US president Ronald Reagan signed a treaty to get rid of some nuclear weapons. Gorbachev started social and economic reforms that gave people freedom of speech; which allowed them to criticise the government and its policies. The ruling communist party lost its grip on the media and the people. Newspapers began printing the many failures that the Soviet Union had covered up and denied in its past. The Soviet Union's economy was lagging and the government was spending a lot of money on competing with the west.

paragraphs: By the 1980s the Soviet economy was suffering but it was stable. Gorbachev's new ideas had gotten out of hand and the communist party lost control. Boris Yeltsin was elected (democratically) the President of the Russian SFSR even though Gorbachev did not want him to come into power. Lithuania announced its independence from the Union and the Soviet government demanded it surrender its independence or it would send the Red Army to keep order. Gorbachev invented the idea of keeping the Soviet Union together with each republic being more independent but under the same leader. He wanted to call it the 'Union of Soviet Sovereign Republics' to keep the Russian initials as CCCP (USSR in English).

paragraphs: A group of communist leaders, unhappy with Gorbachev's idea, tried to take over Moscow and stop the Soviet Union from collapsing. It only made people want independence more. Although he survived the attempted takeover, he lost all of his power outside of Moscow. Russia declared independence in December 1991. Later in the month, leaders of Russia, Byelorussia and Ukraine signed a treaty called the Belavezha Agreement to dissolve the USSR, extremely angering Gorbachev. He had no choice but to accept the treaty and resigned on Christmas Day 1991. The Soviet Union's parliament (Supreme Soviet) made the Belavezha Agreement law, marking formally the dissolution of the Soviet Union. The next day the Soviet flag was lowered from the Kremlin for the last time.


title: Monarch

paragraphs: A monarch is the ruler of a monarchy. Monarchs usually rule because one of their relatives ruled. A male monarch can be a king or emperor. A female monarch can be called a queen or empress.

paragraphs: Where rulers get their power by inheritance because they are a family, they are a dynasty. Monarchs were very common in history. Many countries had a monarch in past centuries, but no longer have them. Some countries that still have monarchs have other leaders that actually have the power.

paragraphs: Monarchs tended to have monarchs of lower honour below them, e.g. a Empire could include several kingdoms, and a kingdom would have several duchies or principalities, nations would rarely include all titles, usually going from duchy to kingdom instead of duchy to principality to kingdom. Prince/Princess means 'Ruler of a Principality' and 'son of king/queen'. Some other languages have separate words for them.


title: Unit

paragraphs: Unit means part of something. It could mean a unit of measurement, or a unit in an army.

paragraphs: Units sometimes means the digit in a number on the right, which is also called the "ones".

paragraphs: For example, a football team may be called "X United". This means that the town of X has come together to support the group.

paragraphs: In the BBC TV series Doctor Who, UNIT (UNified Intelligence Taskforce) is a military group on earth who battle invading aliens.


title: Uncle

paragraphs: An uncle is a name used in an extended family. An uncle is either a brother of one of someone's parents. That person is the uncle's nephew (male) or niece (female). An uncle's child is a cousin. A (also written as great-uncle or grand-uncle) is the brother of a grandparent. In some cultures an uncle is considered a close family member. Based on the old Chinese saying "the oldest son in the family is the father of the family" an uncle is often the head of a family. In many cultures no single word (such as uncle) describes both their parents' brothers. Instead there are words to describe a person's kinship to their mother's brother or a person's kinship to their father's brother. An uncle can also be someone not related by blood or marriage as in a term of endearment or respect. In this use uncle can also be part of a nickname such as Uncle Sam.

paragraphs: During the Middle Ages in western Europe, a maternal uncle played a particular role in the family. A young man was often closer to his maternal uncle (from or "little grandfather") than to his own father. Tacitus noted the Franks had very strong ties between a maternal uncle and his nephew. In Roman family relationships the "avunculus" had a responsibility to defend his nephews as well as his nieces. The maternal uncle relationship was an extension of the Roman kin system's strong brother-sister relationship.

paragraphs: A maternal or paternal relative is one who is related through there parents mother or father respectively. For example a maternal uncle is a the subject's mother's brother.An in-law is a relationship that is not by blood, but instead by marriage. The in-law shares the in-law relationships of the spouses relatives. For example a uncle in-law could be the husband of the subject's Aunt.


title: Information

paragraphs: The word "information" is used in many different ways. Originally, it comes from a word that meant to give a form to something. Information is something that people can learn, know about, or understand. For example, a newspaper contains information about the world. This article contains information about "Information".

paragraphs: People who use computers often use the words "information" and "data" in the same way. There are special fields of study called "information science", "information technology" (IT), and data science.

paragraphs: In the 1970s and 1980s, some people gave a new, specific meaning to "information". At that time, the first computer databases were built. In computer science, "data" often means a kind of information that has not been checked. That means "data" has not been changed or fixed, and you may not be able to trust it. With the new meaning, "information" means data that has been checked and passed tests for what it must be. A person can trust that "information" is correct.

paragraphs: Information can only be correct and good enough to trust if there are very good and complete ways to check the data (data checking, validation or verification) and decide it is good enough (acceptance process). A person must know rules were used to check the data or trust the person who checked the data. If a person cannot tell that this was done, the information still seems to be data for that person, so that person must check the data again, in that general view about data.

paragraphs: The Information Age is a historic period.


title: Airport

paragraphs: An international airport is a large airport that airplanes can use to fly to and from other countries. A domestic airport is an airport which is usually smaller and only has airplanes coming from places in the same country. Most international airports have shops and restaurants for airplane passengers to use.

paragraphs: An airport used by the military is often called an air force base or airbase. An aircraft carrier is a floating airbase.

paragraphs: Airports are made and operated for safety. Today, people must walk through a metal detector, a machine that can tell if metal goes through it. If it makes a noise, the officers will make that person take off all things on them that are metal. They also have X-ray machines that can look into luggage. If officers find items such as weapons, or anything that can be used to kill people, that item (and the person who has it) are taken away and possibly arrested. As well as this, passengers are not allowed to bring bottles or containers with over 100 ml of liquid onto the plane because they could be turned into bombs. Therefore, all water bottles must be emptied before entering the secured area.


title: Ice

paragraphs: Ice is the common name for frozen water. Other liquids, such as ammonia or methane or milk could be called ice when they freeze but they are called 'milk ice', for instance, instead of just 'ice'. Liquid water becomes solid ice when it is very cold. The freezing point is 0° Celsius (32° Fahrenheit or 273 kelvin).

paragraphs: Ice is commonly made in a home refrigerator or freezer. If water is put in a freezer and left for a while, the water gets very cold and will freeze solid, creating ice. Water can be placed into a copper (or other metal) container to cause it freeze into ice faster. Metals are good conductors of heat, so water can freeze faster than in a plastic ice tray.

paragraphs: Unlike other liquids, water expands as it freezes to become ice; so ice floats on water because ice has less density than water. This is very unusual - just about every other liquid gets more dense as it cools; water ice, however, is an important exception. Liquid water expands by about 9% as it becomes ice - it takes up more space. This is because the water molecules are actually farther apart instead of being closer together. The molecules in an ice crystal are arranged in a way that makes it less dense than liquid water.

paragraphs: If water in plumbing freezes, it can burst the water pipe. Water in glass bottles can make them explode when it freezes. Water freezing in rock cracks can expand enough to split hard rocks apart; this is an important geological weathering process that can wear down mountains and make rock into soil.

paragraphs: When materials are cooled their molecules vibrate less and compact together. When most materials reach a temperature called the freezing point, the molecules form a crystalline solid - although some materials (like glass and tar) do not crystallise at all but form super stiff fluids, which seem to be solid. Only Helium will not freeze; all other substances will freeze if cold enough, but fluids like cooking oil, antifreeze, petrol (gasoline), nitrogen, etc. freeze at temperatures that most people don't experience.

paragraphs: Salt water needs a lower temperature to freeze than pure water. The resulting ice contains much less salt than the salt water it came from. This fact has sometimes been used for desalination. Salty ice is not as strong as frozen pure water. Similarly spreading salt on ice melts it, if it's not too cold: the salt progressively eats into the ice, forming brine which does not freeze at that temperature.

paragraphs: Because ice floats, even large bodies of water that freeze, like some oceans, only form ice on the surface. Most lakes never freeze to the bottom. Even the coldest oceans, like the Arctic Ocean, only freeze on the top, leaving liquid ocean circulating below. Because of this the Earth's oceans are able to redistribute heat and the climate of the earth has less extremes of heat and cold than it would otherwise. If ice were to sink instead of float, the oceans would fill with ice from the bottom, would remain solid and only some of the top would thaw. A solid ocean would not circulate heat. But because ice floats on the surface the water beneath can continue to circulate and the ice on the surface stays exposed and readily melts when the temperature rises.

paragraphs: Big bodies of ice on land are called glaciers. Antarctica has the majority of the world's ice.

paragraphs: Climate change happens all the time. When it is very cold it is called an ice age. During ice ages very large areas of the earth are covered in ice, snow and glaciers. The causes of ice ages are complex, or hard to understand. Global warming is currently affecting the Earth's ice resources and its causes are also very complex.

paragraphs: There is also 'dry ice'; it is frozen carbon dioxide. Dry ice exposed to normal air gives off carbon dioxide gas that is odorless and colorless. The gas is so cold that when it mixes with air it cools the water vapour in the air to fog, which looks like a thick white smoke. It is often used in the theatre to make fake fog or smoke.


title: Travel

paragraphs: Travel is the activity of going from one place to another place. When a person makes the same trip every day to work or school, this type of travelling is usually called "commuting." Some people travel to other cities as part of their job. This is called "business travel." When many people travel to a distant place to stay, it is called "human migration".

paragraphs: Some people travel on their vacation, to visit other towns, cities, or countries. This is tourism. These people stay overnight in hotels, hostels, motels, apartments or bed and breakfast. Some prefer camping. Through the centuries, modes of travel have changed. Some people (travel writers) write about travelling in books including autobiographies or journals.


title: CNN

paragraphs: The Cable News Network (CNN) is an American cable news television channel. It was founded in 1980 by Ted Turner. The Cable News Network first aired on television on June 1, 1980. The Cable News Network's first newscast was anchored (hosted) by David Walker and his wife Lois Hart. In its first year CNN hired many political analysts, including Rowland Evans and Robert Novak. On January 1, 1982 CNN launched a 24-hour sister newscast channel with no talk shows or commentary shows called CNN2. CNN broadcasts programs from its headquarters at the CNN Center in Atlanta, or from the Time Warner Center in New York City, or from studios in Washington, D.C., and Los Angeles. CNN is owned by Time Warner, and the U.S. news channel is a part of the Turner Broadcasting System.

paragraphs: The hosts of its opinion shows are Don Lemon, Chris Cuomo, Fredricka Whitfield, Erin Burnett, Brianna Keiler and Brooke Baldwin.

paragraphs: CNN has been criticized by the right-wing Media Research Center for having a left-wing bias. According to that same Center, it is less to the left than the news divisions of ABC, NBC, and CBS. It has been criticized by Arabs for having a pro-American bias.


title: Leader

paragraphs: A leader is somebody whom people follow. A leader has authority. For people to accept a leader, his or her leadership must therefore be legitimate.

paragraphs: Because people follow a leader, the leader can make people do things. A leader can therefore make people work together towards a common goal.

paragraphs: An example of a leader is the head of government of a country. People within the government "follow" the leader, and citizens look to the head of government for inspiration and guidance. Sometimes, when a head of government lacks legitimacy, people will stop following him or her. The head of government is therefore no longer able to lead properly. This may result in a new election, or in worst case civil war.

paragraphs: A group with no leader is called leaderless.


title: Blackboard

paragraphs: A blackboard, also called a chalkboard, is a surface on which chalk is visible. It is used as a surface to write on. It is usually made up of wood or fiber. It is painted black to reflect the white chalks. The high-grade blackboards are made of porcelain enamelled steel.

paragraphs: Blackboards are often used to help in teaching in school. Blackboards are not used as much now but can be seen in some schools still. The chalk dust got everywhere, and some people are allergic to chalk dust. Now people use whiteboards: they can take modern felt-tip colour markers.

paragraphs: Schoolteachers use the chalkboard to display things at large. It also makes the learning cooperative between teachers and student. Chalkboards can be black or dark green, in which case they may be called blackboards and greenboards.


title: Linux

paragraphs: Linux or GNU/Linux is a Unix-like operating system (or strictly family of) for computers. An operating system is a collection of the basic instructions that manage the electronic parts of the computer allowing running applications/programs. Linux kernel (the basis of the operating system) is free software, meaning everyone has the freedom to use it, see how it works, change it, or share it.

paragraphs: There is a lot of software for Linux and—like Linux itself—a lot of the software for Linux is free software. This is one reason why many people like to use Linux.

paragraphs: The defining component of Linux is the Linux kernel, an operating system kernel that Linus Torvalds developed, first alone. Linux is typically packaged in a Linux distribution (or "distro" for short). Distributions also include supporting system software and libraries, many of which are provided by the GNU Project.

paragraphs: Popular Linux distributions include Debian, Fedora, and Ubuntu. Commercial distributions include Red Hat Enterprise Linux and SUSE Linux Enterprise Server. Desktop Linux distributions include a windowing system such as X11 or Wayland, and a desktop environment such as GNOME or KDE Plasma. Distributions intended for servers may omit graphics altogether, and include a solution stack such as LAMP. Because Linux is freely redistributable, anyone may create a distribution for any purpose.

paragraphs: Linux was originally developed for personal computers. Linux is the leading operating system on servers such as mainframe computers, and the only O.S. used on supercomputers (at least on the TOP500 list, since November 2017). It is used by around 2.3% of desktop computers. The Chromebook, which runs the Linux kernel-based Chrome OS, dominates the US K–12 education market and represents nearly 20% of sub-$300 notebook sales in the U.S.

paragraphs: Linux also runs on embedded systems, which are devices whose operating system is typically built into the firmware and is highly tailored to the system; this includes mobile phones (especially smartphones), tablet computers, network routers, facility automation controls, televisions, digital video recorders, video game consoles and smartwatches. In fact, the Android operating system, a mobile operating system built on top of the Linux kernel, has the largest installed base of all general-purpose operating systems. In March 2017, it was reported that there were more users on Android than on Microsoft Windows, which is not based on Linux.

paragraphs: Linux is one of the most prominent examples of free and open-source software collaboration. The source code may be used, modified and distributed—commercially or non-commercially—by anyone under the terms of its respective licenses, such as the GNU General Public License.

paragraphs: In the 1980s, many people liked to use an operating system called Unix. But because it restricted the user from sharing and improving the system, some people made a new operating system that would work like Unix but which anybody could share or improve. MINIX, similar to Unix, was used as a teaching tool for university students to learn how operating systems worked. MINIX also restricted its sharing and improvement by its users.

paragraphs: A group of people called the GNU Project wrote different parts of a new operating system called G.N.U., but it did not have all the parts an operating system needs to work. In 1991 Linus Torvalds began to work on a replacement for MINIX that would be free to use, and which would not cost anything. Linus started the project when he was attending the University of Helsinki. This eventually became the Linux kernel.

paragraphs: Linus Torvalds shared the Linux kernel on some internet groups for MINIX users. Linus first called the operating system "Freax". The name Freax came from joining up the English words "free" and "freak", and adding an X to the name because Unix has an X in its name. Ari Lemmke, who worked with Linus at the University, was responsible for the servers that Freax was stored on. Ari did not think Freax was a good name, so he called the project "Linux" without asking Linus. Later, Linus agreed that Linux was a better name for his project.

paragraphs: Linux relied on software code from MINIX at first. But, with code from the G.N.U. system available for free, he decided it would be good for Linux if it could use that code, instead of code from MINIX, because MINIX did not let people share or change it how they wanted. The G.N.U. General Public License is a software license that lets people change any part of the code they want to, as long as they share any changes they make with the people they give their software to and allow them to redistribute it for free or for a price . The software from G.N.U. was all licensed under the G.N.U. General Public License, so Linus and the other people who worked on Linux could use it too.

paragraphs: To make the Linux kernel suitable for use with the code from the G.N.U. Project, Linus Torvalds started a switch from his original license (which did not allow people to sell it) to the G.N.U. GPL. Linux and G.N.U. developers worked together to integrate G.N.U. code with Linux to make a free operating system.

paragraphs: Since 1991, thousands of programmers and companies have worked to make Linux better including Google.

paragraphs: The mascot of Linux is a cartoon penguin named "Tux". When a person sees the penguin on software and hardware, it means that it will work with Linux, and sometimes all systems that are like Unix.

paragraphs: The idea of the penguin came from the creator of Linux, Linus Torvalds. The image was made by a man named Larry Ewing in a competition to create a logo. The image, Tux, did not win, but it was picked as a mascot later.

paragraphs: Tux has now become a symbol for Linux, and sometimes even for open source. He can be seen in many different places and often, when people refer to Linux, they often think about Tux. Tux has even been included in many video games, such as Super Tux (like Super Mario Bros.), Tux Racer (where players race Tux down an icy hill) and Pingus (like Lemmings).

paragraphs: Although there are only a few Linux versions for some Mac OS X and Microsoft Windows programs in areas like desktop publishing and professional audio and video there are programs that are comparatively similar in quality compared to those available for Mac and Windows.

paragraphs: Many free software programs that are popular on Windows, such as Pidgin, Mozilla Firefox, LibreOffice, Chromium, VLC and GIMP, are available for Linux. A growing amount of proprietary desktop software can also be used under Linux, such as Adobe Flash Player, Spotify and Skype. CrossOver is a proprietary solution based on the open source Wine project that supports running Windows applications such as Microsoft Office and Adobe Photoshop under Linux.

paragraphs: Linux has mainly been used as a server operating system, and has risen to be known by a lot of people in that area; Netcraft reported in February 2008 that five of the ten best internet hosting companies run Linux on their web servers. This is because of its stability and uptime, and the fact that desktop software with a graphical user interface for servers is often unneeded.

paragraphs: Linux is commonly used as an operating system for supercomputers. As of November 2017, all of the top 500 supercomputers run Linux.

paragraphs: In 1992, Torvalds explained how he pronounces the word "Linux":

paragraphs: Torvalds has made available an audio sample which indicates his own pronunciation, in English and Swedish.

paragraphs: Some English speakers pronounce the name as lee-narks or lee-nix or lie-nix. According to Torvalds, that is incorrect pronunciation.

paragraphs: A 2001 study of Red Hat Linux 7.1 found this distribution had 30 million lines of code. The study showed that Red Hat 7.1 required about 8,000 years of time to develop. The study also said that if all this software had been made by proprietary means, it would have cost about $1.08 billion to make in the United States. As of March 7, 2011, Linux kernel would cost about $3 billion.

paragraphs: Version 3.10 of the Linux kernel, released in June 2013, has 15 million lines of code, while the version 4.1, released in June 2015, has grown to over 19.5 million lines of code by almost 14,000 programmers.

paragraphs: Most of the code (around 71%) was written in the C programming language, and many other languages were used, including C++, assembly language, Perl, Python, Fortran, and various shell scripting languages. A little more than half of all lines of code were licensed under the GPL.

paragraphs: People who want to get Linux can download it from a website on the internet or buy it from a store. Sometimes books and magazines about Linux have a CD. or DVD. with Linux on it. Any certain version of Linux is called a "distribution", or "distro". A Linux version has the Linux kernel, G.N.U. software, and some extra programs that might not be a part of G.N.U. Different versions include different extra programs. The versions used by the most people include:

paragraphs: People might pay some money for a version, so they can have a CD-ROM or DVD and to help the company to make their versions better. Usually when someone pays, it is so the company will help the user after they install it, which is called "support".

paragraphs: The Linux kernel and most GNU software are licensed under the GNU General Public License (GPL). The GPL requires that anyone who distributes the Linux kernel must make the source code (and any modifications) available to the recipient under the same terms. In 1997, Linus Torvalds said, "Making Linux GPL'd was definitely the best thing I ever did". Other key components of a Linux system may use other licenses; many libraries use the GNU Lesser General Public License (LGPL), a type of the GPL that is less restricted, and the X Window System uses the MIT License. "Linux" is a trademark of Linus Torvalds.


title: Open source

paragraphs: Open source is a software similar to free software, but is more related to business. It is different from other software because the source code is available to everyone. The source code is a set of instructions for the computer, written in a programming language.

paragraphs: Anyone can see how the source code works and can change it if they want to make it work differently. The opposite of open source is closed source. Closed source software is not available to everyone. Open source has a lot in common with free software but each has its own focus and goals.

paragraphs: Open source and free software have been around for decades. They became more popular with the Linux and BSD software communities. To protect the code, a special user license is used. The most common kinds of licence are the GPL, BSD and LGPL. Wikipedia uses open source too. The Open Source Movement is led by the Open Source Initiative.

paragraphs: The open source movement became separate from the free software movement in 1998.


title: Desktop environment

paragraphs: In graphical user interfaces and consoles a desktop environment is a location on a personal computer that helps the user get around on the computer. The desktop itself is a place in the operating system used for short cuts to computer files and folders on the hard drive. Computer icons (small pictures) are used to represent files/folders. Clicking these icons will open or start a folder or program. The desktop is the area where the start menu is if the computer has a start menu.

paragraphs: Usually the desktop is the main screen on the computer. If no programs or folders are open, the computer will display the desktop.

paragraphs: The most common desktop environment on personal computers is the one given by Microsoft Windows; another common environment is the one given by Apple Mac OS X. Other mostly-used desktop environments for Unix-like operating systems using the X Window System are KDE, GNOME, Xfce. There are also other desktop environments, including : Aston, EDE, GEM, IRIX Interactive Desktop, Sun's Java Desktop System, Mezzo, Project Looking Glass, ROX Desktop, UDE, Xito, XFast.


title: OpenOffice

paragraphs: Apache OpenOffice (formerly OpenOffice.org) is a free open source office suite. The free software project was formerly hosted by Sun Microsystems and then Oracle Corporation and is currently hosted by Apache. It is available for many different operating systems, including Microsoft Windows, Linux, OS X, FreeBSD and Solaris; and is meant to be an alternative to Microsoft Office. It supports Microsoft Office file formats as well as its own OpenDocument format.

paragraphs: The ".org" part of the previous name OpenOffice.org is there because OpenOffice is already trademarked. It is often called "OOo" for short.

paragraphs: OpenOffice is based on the older StarOffice software that was created by Sun Microsystems.

paragraphs: OpenOffice is a collection of applications that work together closely to provide the features expected from a modern office suite. Many of the parts are designed to be alternatives to those available in Microsoft Office. The parts available include:


title: Download

paragraphs: Download means getting information from another computer or server. The opposite of downloading is uploading, which is sending data to another computer. Usually we do not say "download" for a single web page (for example when you open this page on your computer). When we say we downloaded something, it is normally a bigger computer file, like data or a computer program.

paragraphs: The word downloadable means the ability to get information or data from an owner for one's use. The source is expected to be authentic and have the right to send it. At the user's end, the downloaded information or data are to be used based on agreement notice.

paragraphs: In the 21 century, it is very easy to download files or informations - legally or not - from the internet.

paragraphs: As most non-technical users use the word download to talk about any data transfer, the word "sideload" is sometimes used for local to local transfers as distinct from distant ones.


title: GNOME

paragraphs: GNOME is a computer desktop environment. It was designed for Linux, but many other operating systems can use it too. GNOME aims to provide an easy way to use a computer. GNOME is a free software project. It was made because people were questioning whether KDE is free. GNOME is part of the GNU project.

paragraphs: The GNOME project puts heavy emphasis on simplicity, usability, and making things “just work” (see "KISS principle"). The other aims of the project are:

paragraphs: GNOME has many applications written for it. Some of them include:


title: Dog

paragraphs: Dogs ("Canis lupus familiaris") are domesticated mammals, not natural wild animals. They were originally bred from wolves. They have been bred by humans for a long time, and were the first animals ever to be domesticated. There are different studies that suggest that this happened between 15.000 and 100.000 years before our time. The dingo is also a dog, but many dingos have become wild animals again and live independently of humans in the range where they occur (parts of Australia).

paragraphs: Today, some dogs are used as pets, others are used to help humans do their work. They are a popular pet because they are usually playful, friendly, loyal and listen to humans. Thirty million dogs in the United States are registered as pets. Dogs eat both meat and vegetables, often mixed together and sold in stores as dog food. Dogs often have jobs, including as police dogs, army dogs, assistance dogs, fire dogs, messenger dogs, hunting dogs, herding dogs, or rescue dogs.

paragraphs: They are sometimes called "canines" from the Latin word for dog - "canis". Sometimes people also use "dog" to describe other canids, such as wolves. A baby dog is called a pup or puppy. A dog is called a puppy until it is about one year old.

paragraphs: Dogs are sometimes referred to as "man's best friend" because they are kept as domestic pets and are usually loyal and like being around humans. Dogs like to be petted, but only when they can first see the petter's hand before petting; one should never pet a dog from behind.

paragraphs: August 26 is National Dog Day. While March 26 is National Puppy Day.

paragraphs: Dogs have four legs and make a "bark," "woof," or "arf" sound. Dogs often chase cats, and most dogs will fetch a ball or stick.

paragraphs: Dogs can smell and hear better than humans, but cannot see well in color because they are color blind. Due to the anatomy of the eye, dogs can see better in dim light than humans. They also have a wider field of vision.

paragraphs: Like wolves, wild dogs travel in groups called packs. Packs of dogs are ordered by rank, and dogs with low rank will submit to other dogs with higher rank. The highest ranked dog is called the alpha male. A dog in a group helps and cares for others. Domesticated dogs often view their owner as the alpha male.

paragraphs: Different dog breeds have different lifespans. In general, smaller dogs live longer than bigger ones. The size and the breed of the dog change how long the dog lives, on average. Breeds such as the Dachshund usually live for fifteen years, Chihuahuas can reach age twenty. The Great Dane, on the other hand has an average lifespan of six to eight years; some Great Danes have lived for ten years.

paragraphs: All dogs are descended from wolves, by domestication and artificial selection. This is known because DNA genome analysis has been done to discover this. They have been bred by humans. The earliest known fossil of a domestic dog is from 31,700 years ago in Belgium. Dogs have lived with people for at least 30,000 years. In 2013, a study was published that showed that the skull and teeth of a canid, dated to 33,000 years ago, had characteristics closer to a dog than to a wolf, and the authors conclude that "this specimen may represent a dog in the very early stages of domestication, i.e. an “incipient” dog." The researchers go on to suggest that it was, however, a line that did not lead to modern dogs. Genetically, this material is closer to that of a modern dog than to that of a wolf. Other signs of domestication are that sometimes, dogs were buried together with humans. Evidence of this is a tomb in Bonn, where a man of about 50 years of age, a woman of about 25 years of age, the remains of a dog, plus other artifacts were found. Radiocarbon dating showed that the human bones were between 13.300 and 14.000 years old.

paragraphs: Dogs are often called "man's best friend" because they fit in with human life. Man refers to humankind and not just guys (Old English). Dogs can serve people in many ways. For example, there are guard dogs, hunting dogs, herding dogs, guide dogs for blind people, and police dogs. There are also dogs that are trained to smell for diseases in the human body or to find bombs or illegal drugs. These dogs sometimes help police in airports or other areas. Sniffer dogs (usually beagles) are sometimes trained for this job. Dogs have even been sent by Russians into outer space, a few years before any human being. The first dog sent up was named Laika, but she died within a few hours.

paragraphs: There are at least 800 breeds (kinds) of dogs. Dogs whose parents were the same breed will also be that breed: these dogs are called purebred or pure pedigree dogs. Dogs with parents from different breeds no longer belong to one breed: they are called "mutts", "mixed-breed dogs", "hybrids", or "mongrels". Some of the most popular breeds are sheepdogs, collies, poodles and retrievers. It is becoming popular to breed together two different breeds of dogs and call the new dog's breed a name that is a mixture of the parents' breeds' two names. A puppy with a poodle and a pomeranian as parents might be called a Pomapoo. These kinds of dogs, instead of being called mutts, are known as designer dog breeds. These dogs are normally used for prize shows and designer shows.


title: Blindness

paragraphs: Blindness is to not see anything. Some people are called blind, even though they can see a little bit. This is because they cannot see clearly, but only see unfocused shapes or colors.

paragraphs: In modern countries, few young people are blind. In all the world, blindness is mostly caused by malnutrition and diseases of old people, like cataracts and trachoma. People can become blind because of diseases or accidents, but sometimes people are born blind.

paragraphs: Some people are "color blind", which means they can see, but cannot tell certain colors apart.

paragraphs: When people are blind they use such things as the alphabet in "braille" and "guide dogs" to do every day life things.

paragraphs: Famous blind people have included Louis Braille, the inventor of the braille alphabet, Stevie Wonder, Ray Charles and Helen Keller.


title: Arctic

paragraphs: The Arctic is the area around the Earth's North Pole. The Arctic includes parts of Russia, Alaska, Canada, Greenland, Lapland and Svalbard as well as the Arctic Ocean. It is an ocean, mostly covered with ice. Most scientists call the area north of the treeline Arctic. Trees will not grow when the temperatures get too cold. The forests of the continents stop when they get too far north or too high up a mountain. (Higher places are colder, too.) The place where in the trees stop is called the tree line.

paragraphs: The area north of the treeline is not an empty ice field. In fact, the only large ice-covered land is central Greenland, which is covered year-round by a continental glacier. The land of the Arctic is around the edges of the Arctic Circle and is usually covered with tundra. A tundra is a cold, almost treeless plain covered with moss and grasslike plants called "sedges".

paragraphs: Tundras do not get very much rain or snow. However, they are very wet in the summer time because, three feet (1m) or so below the surface, the ground is always frozen. This permafrost is a layer of ice with the hardness of stone that keeps water from soaking into the earth beneath it. Permafrost can be thousands of feet thick. In the summer the ground on top thaws out when the sun shines and the snow that did fall melts. But the melted snow cannot drain into the ground; it just soaks the topsoil. There is no place for the water to go, except to form lakes and puddles on top of the ground until it freezes again or dries up.

paragraphs: In the Arctic, during summer there are nights when the Sun never sets. This is because during summer there, the North Pole points toward the Sun. So, sometimes people call it the Land of the Midnight Sun.

paragraphs: The word comes from the Greek word "αρκτος", meaning "bear". The North Pole aims at the stars called the Great Bear and the Little Bear. This is why it is called the Arctic.

paragraphs: In some parts of the Arctic the ground is covered with bright-colored flowers during the short summer. These little plants have very short stems. They must stay close to the ground, because the earth is warmer than the biting winds that blow above it. Even some rocks have plants growing on them. These rock plants are called lichens. Lichens will grow on the bare rocks. Yellow reindeer moss is really a lichen. It grows slowly, but often grows over six inches (15 cm) tall. It is spongy and full of water. This plant is the summer food for reindeer.

paragraphs: Trees are rare on the tundra. Only in the protected valleys or along the riverbanks are small trees able to grow. Rivers come into the Arctic from the warmer south. The places along their banks are a little bit warmer than the rest of the tundra, and trees can grow there. Otherwise only a few clusters of bushes grow sparingly. Berries are the only fruit that grows in the Arctic.

paragraphs: Each summer the ice and snow melt, allowing the animals to find food and the plants to flower. The moisture from the snow stays toward the top of the ground's surface. Plant roots can use it for their growth. Even so, in many places the soil is too poor for plant's growth. Less than half of the tundra has plants growing on it.

paragraphs: The polar bear is the world's largest meat-eating land animal. Polar bears are well adapted to hunt seals out on the ice. They are excellent swimmers, and the coldest water does not bother them. They wait by breathing holes if they pick up the scent of a seal. They can also break through the ice at thin areas. Sometimes they can sneak up on a sleeping seal. They have a very strong sense of smell, which they use to find prey out on the ice. Polar bears get most of their food when there is pack ice. They must eat and store fat before the ice is gone: they cannot catch seals in open water. After mating, females dig themselves into a den of snow on land for the rest of the winter. There, they have their cubs, usually twins. Bears usually eat fish, birds' eggs, seaweed, and dead whales, but they would rather have a meal of seal or walrus.

paragraphs: The Arctic fox often trails the bears onto the ice to eat their leftover food. The fox also eats rabbits, lemmings, and voles.

paragraphs: The lemmings and voles are the rats and mice of the Arctic. The lemmings have very short tails. They live underground in summer. Because the top soil freezes in the winter, they cannot burrow underground then, so they live under the snow during the colder months. They eat plants and roots. In a year with plenty of food, millions of lemmings will be roaming the tundra. The owls and foxes have more food than they can eat. They will have more young in years when there are many lemmings. However, the tundra does not have enough food for millions of lemmings. They rush across the tundra looking for food, and are eaten by predators or starve to death. Some try to swim across lakes or rivers and drown. The few that remain continue to have families.

paragraphs: Caribou and their relative, the reindeer, also live in the Arctic. The caribou are now found mostly in North America, and they are larger than the reindeer. Large herds feed on the grass and lichens. When fall comes, they move south to winter feeding grounds. They dig through the snow with their sharp hoofs for food. Their hollow fur creates a cushion of air around them that helps them to stay warm. In the spring they return north to the summer pastures, where their calves are born. An hour or so after being born, the calves are able to follow the herd toward the Arctic Ocean. Most of the world's reindeer live in Europe and Asia. Some of these reindeer are not wild. They have been tamed by herdsmen who protect them from wolves and lead the migrations each spring and fall. Also, the musk ox, which looks like a shaggy buffalo, lives in the Arctic.

paragraphs: In summer, many birds visit the Arctic, and most of them are water birds, such as geese, ducks, swans, loons, and Arctic terns. Flying in for the summer, they raise their young and return south for the winter. The snowy owl and the ptarmigan stay all year. The color of the snowy owl matches the snow. The ptarmigan's summer plumage changes to white when it gets colder.

paragraphs: The smallest animals of the Arctic are the flies and the mosquitoes. Thick swarms bite both men and animals in the summer. The reindeer try to escape the mosquitoes by running to higher pastures, but the only real help comes with the snow and cold, when the swarms die off for another season.

paragraphs: One of the surprises of the Arctic is that many people live there. Some people have lived there for thousands of years. Eskimo and Lapp people lived in the Arctic long before electric heaters, snow-mobiles, and modern houses.

paragraphs: In an extremely northern part of Europe there is a place called Lapland. It is not a country, but parts of four countries. The people who lived there are called Lapps by outsiders. They call themselves "Sami". The Lapps of these four countries lived there long before the countries of Northway, Sweden, Finland, and Russia were created. There were several kinds of Lapp people. Some lived by the ocean and lived mostly on fish. Another group lived along the warmer rivers. These people did a little farming, hunting, and fishing to live.

paragraphs: But the best known of the Lapp people were the nomads who raised reindeer. The Lapps survived in their harsh homeland by domesticating the reindeer. The Lapps were able to get everything they needed from the deer. They ate mostly meat, milk, and cheese. Their clothes were made froom reindeer skins and wool. Their tents were also made from deer skins. They are known for the beautifully decorated woolen clothing they made.

paragraphs: The Lapps protected the herds, moving with them as they migrated from summer to winter pastures. They used trained reindeer to pull sleds carrying their supplies. During the winter, the herds moved south of the treeline. The Lapps would live nearby in homes made of logs or sod. The Lapps were very careful not to waste anything they got from the reindeer. Milk was taken from the reindeer to drink or make cheese. Meat was taken for food. The blood was frozen in chunks and used for soup and pancakes. Knives and belt buckles were carved from the bones and antlers. The sinews were used as sewing thread. Cleaned-out stomachs were used to carry milk or cheese. Every part of a dead reindeer was used.

paragraphs: Winter clothing was made from layers of deer skin. The inside layer would be worn with the fur facing in toward the person's skin. The second layer was worn with the fur facing out. Boots were also made of fur, lined with grass that had been gathered during the short summer. Every evening the grass would be taken out and dried by the fire, so it would be ready to use again the next day. Thus, a Lapp could be warm and comfortable in even the coldest weather.

paragraphs: Today only a few of the Lapp people still follow the herds. Those few use modern tools on their ancient migration. They use snowmobiles to herd the reindeer and rifles to kill the wolves that chase them. Even helicopters and radios are used to locate and move the reindeer. Most of the Lapp people now live on small farms in one of the four nations of Lapland. They raise crops and animals, including a few reindeer, to meet their needs. The sale of reindeer meat is an important source of income for the Lapp people.

paragraphs: Eskimos are Arctic people, too. They sometimes ate raw meat. Eskimos were also nomads, but they did not have any animals except for dogs, which they used for pulling their sleds and helping them hunt. They were hunters and gatherers, and they lived off on whatever they found or killed. Like the Lapps, though, they were very careful to make good use of every part of the animals they killed. Eskimos lived in tents during the summer, and sod houses or igloos in the winter. The Eskimos made very clever things from the bones, antlers, and wood they had. They built different kinds of boats.

paragraphs: Eskimos did not have a government or laws, because they learned early in life to help each other in order to survive. Always sharing food, they usually moved around in small groups looking for food. Sometimes they'd get together in a large group when they hunted big animals such as whales. The men did the hunting and building the homes, and the women cooked, made the clothes, and took care of the children.

paragraphs: The Arctic region has many minerals that are important to people. Iron, lead, coal, copper, gold, and tin are all mined in different parts of this cold land. Large amounts of petroleum have been discovered in the Arctic in Russia, Alaska, and Canada. People live and work in the Arctic to remove these valuable minerals and sell them.

paragraphs: The oil in Alaska, for example, is very important to the United States. The main source is the Prudhoe Bay Oil Field on Alaska's north coast. It was discovered in 1968. Plans were quickly made to build a pipeline to bring the oil to an ice-free port so it could be shipped south. Oil companies spent billions of dollars to build the Trans-Alaska Pipeline in the mid-1970s. It had to be built above the ground in the northern section because of the permafrost. The warm oil in the pipes could have melted the permafrost and caused the ground to sink. That would have broken the pipes and caused an oil spill. The pipeline was completed in 1977. It brings oil to the seaport of Valdez on Alaska's south coast. From there the oil is taken by huge tankers to refineries along the west coast of the United States. If you live in western America, your family car may have Alaskan gasoline in its tank.

paragraphs: Russia has more land in the Arctic than any other nation. The Russian Arctic in Asia and the area just south of it are called Siberia. It is such an empty, harsh place that it has been used as a penal colony for many years. The old Russian rulers and the modern communist Soviets would send criminals and people who disagreed to the government to live there. However, many people were also sent there to remove minerals, harvest trees from forests, and build cities.

paragraphs: Russia has a huge port city right in Lapland, within the Arctic Circle. Murmansk is the largest city north of the Arctic Circle. The port is kept ice-free by the warm waters of the Gulf Stream coming up around Norway and Sweden from the South Atlantic. Huge icebreakers work to keep a path open so ships can reach the port. The port ships out fish, minerals, and lumber to Russia and the rest of the world.

paragraphs: The Arctic is also the shortest way (Great circle route) for airlines to fly between some cities on different continents. The flight from London to Tokyo, for example, is 1,400 miles shorter if flown across the top of the world instead of the old route south across Europe and Asia. The polar route from San Francisco to Norway is several hours shorter than the same flight going across the United States and the Pacific Ocean.

paragraphs: Thus, man is making use of the Arctic in various ways even though it is a hard place to live.


title: Sin

paragraphs: A sin is a bad act. Particularly, it is a bad act against another person(s), an animal, a spirit, or a god.

paragraphs: In Abrahamic religions, such as Christianity and Judaism, it is an act that goes against what God wants. It turns people away from God and true happiness. In Exodus chapter 20, Moses was given the Ten Commandments by God, explaining important sins like murder and idolatry. This is not believed by all people, and not all societies have the same idea of sin.

paragraphs: There is a difference between sins and prohibitions. For example, Muslims and Jews say that it is wrong to eat pork, and Hindus do not eat beef. That is for them, but for others it is not wrong to eat these things.


title: Summer

paragraphs: Summer is one of the four seasons. It is the hottest season of the year. In some places, summer is the wettest season (with the most rain), and in "other places", it is a dry season. Four seasons are found in areas which are not too hot or too cold. Summer happens to the north and south sides of the Earth at opposite times of the year. In the north part of the world, summer takes place between the months of June and September, and in the south part of the world, it takes place between December and March. This is because when the north part of the Earth points towards the Sun, the south part points away.

paragraphs: Many people in rich countries travel in summer, to seaside resorts, beaches, camps or picnics. In some countries, they celebrate things in the summer as well as enjoying cool drinks. Other countries get snow in the summer just like winter.


title: Month

paragraphs: A month is an amount of time used with calendars. It is about 1/12th of a year. It is a little longer than a natural synodic orbital period of the moon, ca. 29.5 days. Lunar calendars use the natural synodic month. For some purposes astronomers use the sidereal month of 27.3 days.

paragraphs: Other calendars, called "solar calendars", ignore the moon, and depend entirely on the Sun — for example, the Gregorian calendar of 365 or 366 days (12 months) used in much of the world today.


title: Alberta

paragraphs: Alberta is a province in western Canada. It is bounded by the provinces of British Columbia on the west, Saskatchewan on the east, the US state of Montana on the south and the Northwest Territories to the North.

paragraphs: Alberta is the fourth largest Canadian province with an area of 642,317 km². Alberta has more or less than 3,305,800 people making it the fourth most populous province in Canada.

paragraphs: The capital of Alberta is Edmonton lying near the middle of Alberta. The city of Calgary, Alberta’s other major centre, is located about 300 kilometres to the south.

paragraphs: Canada became a country in 1867. It was much smaller than it is now, and did not include the parts of the country to the west. From 1670 to 1870, parts of Alberta were included in "Rupert's Land," land owned by the Hudson’s Bay Company in support of it’s trading monopoly over a vast area of Canada and parts of the United States. Northern part of Alberta was part of the what was then called "Northwestern Territories."

paragraphs: Alberta was made a province of Canada in 1905, at the same time as Saskatchewan.

paragraphs: The Aboriginal peoples of Canada are referred to as First Nations or by the Name of their Nation. Mixed (European/Aboriginal) People are called Metis.

paragraphs: Alberta is very cold in the winter and has a lot of snow during the very cold season. There is a dry part of Alberta in the south.

paragraphs: Alberta has a huge amount of oil (in the Athabasca Oil Sands) and natural gas.

paragraphs: There are also a lot of farms in Alberta. Farmers grow several different types of crops Farmers mainly grow wheat. There are also a lot of cows on Alberta farms, and Alberta beef is exported.


title: Electronics

paragraphs: Electronics is the study of how to control the flow of electrons. It deals with circuits made up of components that control the flow of electricity. Electronics is a part of physics and electrical engineering.

paragraphs: Electrical components like transistors and relays can act as switches. This lets us use electrical circuits to process information and transmit information across long distances. Circuits can also take a weak signal (like a whisper) and amplify it (make it louder).

paragraphs: Most electronic systems fall into two categories:

paragraphs: One way of looking at an electronic system is to separate it into three parts:

paragraphs: A television set, for example, has as its input a broadcast signal received from an antenna, or for cable television, a cable.

paragraphs: Signal processing circuits inside the television set use the brightness, colour, and sound information contained in the received signal to control the television set's output devices. The display output device may be a cathode ray tube (CRT) or a plasma or liquid crystal display screen. The audio output device might be a magnetically driven audio speaker. The display output devices convert the signal processing circuits' brightness and colour information into the visible image displayed on a screen. The audio output device converts the processed sound information into sounds that can be heard by listeners.

paragraphs: Analysis of a circuit/network involves knowing the input and the signal processing circuit, and finding out the output. Knowing the input and output and finding out or designing the signal processing part is called "synthesis".

paragraphs: People started experimenting with electricity as early as 600 B.C.E, when Thales of Miletus discovered rubbing fur on amber would cause them to attract each other.

paragraphs: Starting in the 1900s, devices used glass or metal vacuum tubes to control the flow of electricity. With these components a low power voltage can be used to change another. This revolutionized radio, and allowed other inventions.

paragraphs: In the 1960s and early 1970s transistors and semiconductor began replacing vacuum tubes. Transistors can be made much smaller than vacuum tubes and they can work using less energy.

paragraphs: At about the same time, integrated circuits (circuits that have a large numbers of very small transistors placed on very thin slices of silicon) became commonly used. Integrated circuits made it possible to reduce the number of parts needed to make electronic products and made the products much cheaper in general.

paragraphs: Analog circuits are used for signals that have a range of amplitudes. In general, analog circuits measure or control the amplitude of signals. In the early days of electronics, all electronic devices used analog circuits. The frequency of the analog circuit is often measured or controlled in analog signal processing. Even though more digital circuits are made, analog circuits will always be necessary, since the world and its people work in analog ways.

paragraphs: Pulse circuits are used for signals that require rapid pulses of energy. For example, aircraft and ground radar equipment work by using pulse circuits to create and send high powered bursts of radio energy from radar transmitters. Special antennas (called "beam" or "dish" antennas because of their shape) are used to send ("transmit") the high powered bursts in the direction the beam or dish antenna is pointed.

paragraphs: The radar transmitter's pulses or bursts of radio energy hit and bounce back (they are "reflected") from hard and metallic objects. Hard objects are things like buildings, hills, and mountains. Metallic objects are anything made of metal, like aircraft, bridges, or even objects in space, like satellites. The reflected radar energy is detected by radar pulse receivers which use both pulse and digital circuits together. The pulse and digital circuits in radar pulse receivers are used to show the location and distance of objects which have reflected the radar transmitter's high powered pulses.

paragraphs: By controlling how often the rapid pulses of radar energy are sent out by a radar transmitter (called the transmitter's "pulse timing"), and how long it takes for the reflected pulse energy to come back to the radar receiver, one can tell not only where objects are, but also how far away they are. Digital circuits in a radar receiver calculate the distance to an object by knowing the time interval between energy pulses. The radar receiver's digital circuits count how long it takes between pulses for an object's reflected energy to be detected by the radar receiver. Since radar pulses are sent and received at approximately the speed of light, the distance to an object can easily be calculated. This is done in digital circuits by multiplying the speed of light by the time it takes to receive the radar energy reflected back from an object.

paragraphs: The time between pulses (often called "pulse rate time", or PRT) sets the limit on how far away an object can be detected. That distance is called the "range" of a radar transmitter and receiver. Radar transmitters and receivers use long PRT's to find the distance to objects that are far away. Long PRT's makes it possible to accurately determine the distance to the moon, for example. Fast PRT's are used to detect objects that are much closer, like ships at sea, high flying aircraft, or to determine the speed of fast moving automobiles on highways.

paragraphs: Digital circuits are used for signals that only turn on and off instead of often working at levels somewhere between on and off. Active components in digital circuits typically have one signal level when turned on, and another signal level when turned off. In general, in digital circuits a component is only switched on and off.

paragraphs: Computers and electronic clocks are examples of electronic devices that are made up of mostly digital circuits.


title: Scalar

paragraphs: Scalars are simple numbers. They are used for measuring things. Many things can be measured, and the measure can be explained by only giving the number.

paragraphs: Suppose we are measuring a rod. We could give the measured length as 2 metres or 3 cm—depending on the length of the rod under observation. Here, only the figure 2 or 3 along with the unit of measure is enough to transmit information about the rod.

paragraphs: In other words, mass is measured by scalars, just like distances are measured by scalars.

paragraphs: In mathematics, scalars are distinguished from more complex mathematical objects such as vectors and matrices in that they consist of only one number. A scalar formula_1 can also be multiplied to a vector formula_2 or a matrix formula_3, resulting in the vector formula_4 and the matrix formula_5, respectively. For vectors, scalar multiplication produces a new vector of different length in the same or opposite direction of the original vector.


title: Photon

paragraphs: Photons (from Greek φως, meaning "light"), in many atomic models in physics, are particles which transmit light. In other words, light is carried over space by photons. Photon is an elementary particle that is its own antiparticle. In quantum mechanics each photon has a characteristic quantum of energy that depends on frequency: A photon associated with light at a higher frequency will have more energy (and be associated with light at a shorter wavelength).

paragraphs: Photons have a rest mass of 0 (zero). However, Einstein's theory of relativity says that they do have a certain amount of momentum. Before the photon got its name, Einstein revived the proposal that light is separate pieces of energy (particles). These particles came to be known as photons.

paragraphs: A photon is usually given the symbol γ (gamma),

paragraphs: Photons are fundamental particles. Although they can be created and destroyed, their lifetime is infinite.

paragraphs: In a vacuum, all photons move at the speed of light, c, which is equal to 299,792,458 meters (approximately 300,000 kilometers) per second.

paragraphs: A photon has a given frequency, which determines its color. Radio technology makes great use of frequency. Beyond the visible range, frequency is less discussed, for example it is little used in distinguishing between X-Ray photons and infrared. Frequency is equivalent to the quantum energy of the photon, as related by the Planck constant equation,

paragraphs: where formula_2 is the photon's energy, formula_3 is the Plank constant, and formula_4 is the frequency of the light associated with the photon. This frequency, formula_4, is typically measured in cycles per second, or equivalently, in Hz. The quantum energy of different photons is often used in cameras, and other machines that use visible and higher than visible radiation. This because these photons are energetic enough to ionize atoms.

paragraphs: Another property of a photon is its wavelength. The frequency formula_4, wavelength , and speed of light formula_7 are related by the equation,

paragraphs: where formula_9 (lambda) is the wavelength, or length of the wave (typically measured in meters.)

paragraphs: Another important property of a photon is its polarity. If you saw a giant photon coming straight at you, it could appear as a swath whipping vertically, horizontally, or somewhere in between. Polarized sunglasses stop photons swinging up and down from passing. This is how they reduce glare as light bouncing off of surfaces tend to fly that way. Liquid crystal displays also use polarity to control which light passes through. Some animals can see light polarization.

paragraphs: Finally, a photon has a property called spin. Spin is related to light's circular polarization.

paragraphs: Light is often created or absorbed when an electron gains or loses energy. This energy can be in the form of heat, kinetic energy, or other form. For example, an incandescent light bulb uses heat. The increase of energy can push an electron up one level in a shell called a "valence". This makes it unstable, and like everything, it wants to be in the lowest energy state. (If being in the lowest energy state is confusing, pick up a pencil and drop it. Once on the ground, the pencil will be in a lower energy state). When the electron drops back down to a lower energy state, it needs to release the energy that hit it, and it must obey the conservation of energy (energy can neither be created nor destroyed). Electrons release this energy as photons, and at higher intensities, this photon can be seen as visible light.

paragraphs: In particle physics, photons are responsible for electromagnetic force. Electromagnetism is an idea that combines electricity with magnetism. One common way that we experience electromagnetism in our daily lives is light, which is caused by electromagnetism. Electromagnetism is also responsible for charge, which is the reason that you can not push your hand through a table. Since photons are the force-carrying particle of electromagnetism, they are also gauge bosons. Some matter–called dark matter–is not believed to be affected by electromagnetism. This would mean that dark matter does not have a charge, and does not give off light.


title: Vector

paragraphs: A vector is a mathematical object that has a size, called the "magnitude", and a direction. It is often represented by boldface letters (such as formula_1, formula_2, formula_3), or as a line segment from one point to another (as in formula_4).

paragraphs: For example, a vector would be used to show the distance and direction something moved in. When asking for directions, if one says "Walk one kilometer towards the North", that would be a vector, but if they say "Walk one kilometer", without showing a direction, then that would be a scalar.

paragraphs: We usually draw vectors as arrows. The length of the arrow is proportional to the vector's magnitude. The direction in which the arrow points to is the vector's direction.

paragraphs: The Head to Tail method of adding vectors is useful for doing an estimate on paper of the result of adding two vectors. To do it:

paragraphs: It's called the "Head to Tail" method, because each head from the previous vector leads in to the tail of the next one.

paragraphs: Using the component form to add two vectors literally means adding the components of the vectors to create a new vector. For example, let a and b be two two-dimensional vectors. These vectors can be written in terms of their components.

paragraphs: Suppose c is the sum of these two vectors, so that c = a + b. This means that formula_7.

paragraphs: Here is an example of addition of two vectors, using their component forms:

paragraphs: This method works for all vectors, not just two dimensional ones.

paragraphs: The dot product is one method to multiply vectors. It produces a scalar. It uses component form:

paragraphs: The cross product is another method to multiply vectors. Unlike dot product, it produces a vector. Using component form:

paragraphs: Here, formula_13 means the length of formula_14, and formula_15 is the unit vector at right angles to both formula_14 and formula_17.

paragraphs: To multiply a vector by a scalar (a normal number), you multiply the number by each component of the vector:


title: Soap bubble

paragraphs: A soap bubble is a very thin film of soap water. Their shape is a hollow, round ball, or sphere. They have a colorful surface. Soap bubbles do not last very long. Sometimes they break in the air. When they touch something else, they usually break. When people talk about soap bubbles they think about them being pretty but short-lived. So, they are a symbol for other things that are pretty but short-lived or unimportant. Children enjoy playing with bubbles. Sometimes, adults enjoy seeing art done with soap bubbles.


title: Fire Brigades Union

paragraphs: The Fire Brigades Union (FBU) is the main union for firefighters in the United Kingdom. A union is a group of workers. They make the group to improve pay and working conditions. It was founded in 1918 in the London area as the "Firemans Trade Union". It soon grew to cover the entire country. Today, it has around 50,000 members.


title: Bicycle

paragraphs: A bicycle (or bike) is a small, human powered land vehicle with a seat, two wheels, two pedals, and a metal chain connected to cogs on the pedals and rear wheel. A frame gives the bike strength, and the other parts are attached to the frame. The name comes from these two words - the prefix "bi-" meaning two, and the suffix "-cycle" meaning wheel. It is powered by a person riding on top, who pushes the pedals around with his or her feet.

paragraphs: Riding bicycles, which is also called cycling, is an important way to travel in several parts of the world. The most popular type of cycling is Utility cycling. It is also a common recreation, a good form of low-impact exercise, and a popular sport. Road bicycle racing is the second most popular spectator sport in the world.

paragraphs: Bicycling uses less energy per mile than any other human transport.

paragraphs: In 1817 a German professor, Baron Karl von Drais, created the first two-wheeled bicycle. It was made of wood and had two wheels. The front wheel could be turned using the handlebars in order to steer the bike. However, it did not have pedals, so the rider would have to push their feet on the ground to make it move.

paragraphs: In the 1860s, French inventors added pedals to the front wheel. However, it took a lot of effort to turn the pedals. Later inventors made bikes out of metal only, and made the front wheel very big, giving higher speed. This design was called the penny-farthing bicycle. However, it was difficult to ride, since it could fall easily and the rider would fall far.

paragraphs: Several improvements were made in the 1880s and '90s. In 1885, the safety bicycle was invented. This had two wheels the same size so that the rider could sit at a lower height. It was called the safety bicycle because it much easier to ride than the penny-farthing. When stopping, the rider can simply put down a foot instead of completely dismounting. Instead of pedaling and steering with the front wheel, the safety bicycle steers with the front wheel while the pedals turn the back wheel using a chain. Brakes operated by hand levers on some bikes also increased safety.

paragraphs: In 1888, Scottish inventor John Boyd Dunlop re-invented a type of tire which was filled with air. This made safety bicycles more comfortable. Soon, the freewheel was invented. This was a device inside the hub of the back wheel that allowed the wheel to spin even if the rider wasn't pedaling. However, this meant the rider could no longer stop the bike by backpedaling. As a result, better hand brakes were invented, and a different type of brake which could stop the bike if the pedals were turned backwards. Later inventions included better brakes, and gears which made cycling over hills much easier. During this time the bicycle became very popular.

paragraphs: Basic components common to most bikes include a seat, pedals, gearing, handlebar, wheels, and brakes, all mounted on a frame. The majority also have a gear shifter. The cyclist's feet push the pedals to make them go around in circles, which moves the chain, which turns the back wheel of the bike to make the bike move forwards. The front wheel is connected to the handlebar, so turning the handlebar from side to side swivels the front wheel which steers the bike.

paragraphs: When riding on streets, it is safest to ride on the same side of the street that cars drive (which would mean riding on the right side of the road in countries where people drive on the right side of the road, and riding on the left in countries where people drive on the left). To avoid hitting people, riders must obey signs that say "no bicycling", even if it does not seem to make sense at the time. Low light makes bicycle lighting important. It may not be safe to ride when it is dark. Riders wear reflective clothing to be safer in low light. Wearing a helmet makes bicycle riding safer. More than 300,000 people children alone to go to a hospital every year because they were hurt riding a bicycle. Wearing a helmet does not mean that somebody cannot be hurt if they crash their bicycle, but it makes being hurt less likely. Some bicycles have bells or horns that the rider can use to warn other people that they are riding by them.

paragraphs: Many places have a bicycle path linking houses with shops, schools and stations. These make bicycling safer, letting cyclists stay away from busy motor traffic on dangerous roads. Bike shelters can also help in keeping the bike and a rider safe.


title: Wheel

paragraphs: A wheel is a disc or circle-shaped mechanical device. Its main purpose is to allow things to "roll"; in other words, the wheel spins, and object on the wheels moves more easily along the ground. It is a simple machine.

paragraphs: Most land vehicles roll on wheels. Wheels are often used in pairs, connected by a rod of wood or metal known as an axle. Many machines have wheels with teeth, known as gears. The principle behind the wheel is that of mechanical advantage.

paragraphs: This is a machine in which the wheel and axle turn together. It is the basis of many machines, not just vehicles. The potter's wheel, the lathe and the windlass are examples.

paragraphs: Most experts believe that the ancient Mesopotamians invented the wheel about 4000 BC.

paragraphs: People in Asia also discovered it on their own around 3500 BC. The Inca and Maya had wheels on children's toys around 1500 BC, but they did not use wheels for work. Africa south of the Sahara desert, Europe, and Australia did not have the wheel until people there met people from Europe. Early wheels were solid disks; the spoked wheel was invented around 2000 BC. The earliest documentation of a vehicle with wheels is a painting dated between 33503500 BC.


title: Physical exercise

paragraphs: People do physical exercises as a part of their healthy lifestyle to get stronger and healthier or stay strong and healthy or to improve their body image. There are three basic modes of physical exercises:

paragraphs: Exercises can be an important part of physical therapy, weight loss, or sports performance.

paragraphs: Exercise can be fun, but it is important for the exerciser to do what he likes and eat enough calories , so when he exercises he is building up muscles, not just breaking them down for fuel. Carbohydrates are muscle-sparing; and if one does not get enough calories overall, there is the risk of burning muscles up with the fat to make up the deficit.

paragraphs: Benefits of exercise for all ages have been known since antiquity. Marcus Cicero, around 65 BC, stated: “It is exercise alone that supports the spirits, and keeps the mind in vigor.”

paragraphs: Regular exercise has been shown to help high blood pressure, obesity, heart disease, diabetes, and depression, among others. Exercise also helps people feel less tired.


title: Percentage

paragraphs: Percent means "out of one hundred". It is often shown with the symbol "%". It is used even if there are not a hundred items. The number is then scaled so it can be compared to one hundred. Percent is also used to indicate changes in numerical quantities.

paragraphs: For example, we have a bowl of fruit with three apples and one orange. The percentage of apples is 3 out of 4, or 3/4 = 75/100 = 75%.

paragraphs: A percentage is only one way of writing a ratio; one can also write it as a fraction or decimal. There are ways to convert fractions to percentages or decimals to percentages.

paragraphs: Percentages are useful in practice, because it allows one to compare things that are not out of the same number. For example, exam marks are often percentages, which can compare them even if there are more questions on one exam paper than the other.