juno-labs/simple_wikipedia huggingface dataset:
Shaanxi

**Shaanxi** (Chinese:陕西, also sometimes called **Shenshi**) is a province in northwest China. The word "Shaan" (viz Shanzhou) is a place in Henan Province. "Xi" means "west". So "Shaanxi" means "the place to the west of Shaan".

Although in pinyin, "Shaanxi" is spelled exactly the same as "Shanxi", the only difference in how the two words are pronounced is that the first syllable in "Shanxi" is said using the first tone in Mandarin, while the first syllable in "Shaanxi" is said with the third tone. Since tone markers are not usually used to show how to pronounce the two different names, the first word in "Shaanxi" is spelled using the Gwoyeu Romatzyh method instead, which indicates tones by adding extra letters to a syllable.

The river Wei He runs across it. It has a large population of more than 30 million people. The capital of Shaanxi is Xi'an. It abbreviates as **Shan** (陕) or **Qin** (秦), also known as **SanQin** (三秦, meaning _Three Qins_).

## History

January 23, 1556 – A massive earthquake, measuring 9.0 on the Richter scale, strikes Shaanxi, killing over 850,000 people. This is the most devastating earthquake in recorded history.

## Political divisions

Shaanxi Province is divided into ten municipalities:

1. Xi'an Municipality(西安市)
1. Ankang Municipality(安康市)
1. Baoji Municipality(宝鸡市)
1. Hanzhong Municipality(汉中市)
1. Shangluo Municipality(商洛市)
1. Tongchuan Municipality(铜川市)
1. Weinan Municipality(渭南市)
1. Xianyang Municipality(咸阳市)
1. Yan'an Municipality(延安市)
1. Yulin Municipality(榆林市)
Surfing

**Surfing** is a water sport done in the ocean or sea. The surfer uses their surfboard to catch a wave and ride in towards the shore.

Surfing was invented by the Polynesians at least 4000 years ago. Surfing made its Olympic debut at the 2020 Summer Olympics in Tokyo, Japan. It has become a popular sport among both men and women of all ages. With lifestyles and regimens freer than those of most sports, surfers comprise a unique culture. Though surfing is practiced in many other Pacific nations, its center remains Hawaii, where many rounds of the international surfing championships (the ASP) are held annually. Surfing is popular in Australia, the US, and Northern Europe.

## Related pages

- Skimboarding
- Windsurfing
Lyon

**Lyon** (Arpitan: _Liyon_) is a city in the southeast of France. It is the third-largest city in the country (behind Paris and Marseille), with about 520,774 people living there in 2022. It is the second largest _metropolis_, or metro area, in France (behind only that of Paris), with 2,327,861 people in 2022.

In ancient history, the name of Lyon was _Lugdunum_. Someone who lives in Lyon is called a _Lyonnais_ (male) or a _Lyonnaise_ (female) in French.

Lyon has a humid subtropical climate (_Cfa_ in the Koeppen climate classification). It is between the Rhône and the Saône. It is about  west of the Italian border.

The central part of Lyon, located on the peninsula between the Rhône and the Saône, was named a World Heritage Site by UNESCO.

## Famous people from Lyon

- The Lumière Brothers who created cinema
- Paul Bocuse, a world renowned chef

## Sports

Famous sports clubs from Lyon are:

- Olympique Lyonnais: The local football team that plays in Ligue 1
- ASVEL: The local basketball team
- LOU: (Lyon Olympique Universitaire) The local rugby team

## Education

- École Centrale de Lyon
- École pour l'informatique et les nouvelles technologies
- École pour l'informatique et les techniques avancées
- École spéciale de mécanique et électricité
- EMLYON Business School
- E-Artsup
- Institut Polytechnique des Sciences Avancées
- Institut supérieur européen de gestion group
- Institut supérieur européen de formation par l'action
- Sup'Biotech
- Web@cademie

## Infobox (settlement)

- **name**: Lyon
- **image shield**: Blason Ville fr Lyon.svg
- **leader party**: La République En Marche!
- **subdivision name3**: Arrondissement of Lyon
- **subdivision type3**: Arrondissements of France, Arrondissement
- **subdivision name2**: Lyon Metropolis
- **subdivision type2**: Territorial collectivity, Metropolis
- **subdivision name1**: Auvergne-Rhône-Alpes
- **subdivision type1**: Regions of France, Region
- **subdivision name**: France
- **subdivision type**: List of countries, Country
- **flag size**: 205
- **elevation ft**: 531-1,145
- **elevation m**: 162-349
- **pop est as of**: January 2022
- **population est**: 520,774
- **leader name**: Gerard Collomb
- **leader title**: Mayor (2018-)
- **parts type**: arrondissements
- **image flag**: Flag of Lyon, France.svg
- **settlement type**: Commune
- **population metro**: 2,327,861
Organic compound

**Organic compounds** are carbon-based compounds. Organic compounds contain carbon bonds in which at least one carbon atom is covalently linked to an atom of another type (usually hydrogen, oxygen or nitrogen). Most polymers are organic compounds.

## History

The name "organic" is a historical name from the 19th century.

People believed that only living things could make organic compounds and "dead" things (such as minerals) could make inorganic compounds. However, Friedrich Wöhler proved this wrong by synthesizing urea, a well-known organic compound.

## Kinds of organic compounds

There are natural organic compounds, and synthetic ones. Their structure may be described by using names, and making diagrams.

One way of showing the molecule is by drawing its structural formula. Because molecules can have complicated structures, people have made ways to show them in simple language. One way is to use line diagrams. Each atom is shown by a letter, and connected by a line to each atom with which it is has a covalent bond. One line means a single bond, two lines means a double bond and so on.

Because there is in an infinite number of possible organic compounds, language is needed to give a unique name to each one. The International Union of Pure and Applied Chemistry, or IUPAC, made a system for doing this. Although an IUPAC name makes every single possible molecule unique, the names are often long and complicated, so in everyday life, _trivial_ names--unofficial but widely understood names--are used, such as the trivial names Paracetamol, Tylenol, and Acetaminophen, which are used for a compound whose IUPAC name is _N-(4-hydroxyphenyl) acetamide_. Some of these trivial names are trademarks.

### Natural compounds

Natural compounds are compounds made by living beings. These could also be made in a lab, but many of these compounds are taken from nature because it is easier and less expensive to do it that way. For example, every year people grow and eat huge amounts of natural sugar and starch. Other common natural compounds are: amino acids, proteins, carbohydrates, many antibiotics like Penicillin and Amoxicillin.

### Synthetic compounds

Synthetic compounds are those made by people. Sometimes, this is done by taking something natural and changing the molecule in a small way, such as making glycerin from vegetable oils. Other compounds are synthesized in long, complicated reactions with many steps. Plastics are sometimes mostly natural, and other kinds are manufactured.

## Structure

Since a compound is often first discovered in nature instead of being made on purpose in a lab, people may know the compound exists, and even know what it does sometimes, but not know exactly what atoms it is made of and how it is arranged. There are several ways of taking an unknown compound and finding out this structure:
- Mass spectrometry
- X-ray diffraction
- Nuclear magnetic resonance spectroscopy
- Infrared spectroscopy

## Related pages

- Acetone
- Inorganic compound
- Organic chemistry
- Biochemistry

## Other websites

- Organic chemistry online
Natural gas

**Natural gas** is a mixture of gas<nowiki/>es. It consists mainly of hydrocarbons. The main component is methane, which is a greenhouse gas. Natural gas is a natural resource, often found in the ground, either alone or together with petroleum. Landfills and natural processes produce a little methane. Usually it is transported to users in a pipeline.

Most natural gas is burnt as a fuel to produce energy. It burns with a blue flame. Like other flames, this can cause pollution with nitrogen oxides.

Natural gas is burned to produce electricity, to cook and to heat buildings. It is also used as fuel for natural gas vehicles for transport. When natural gas is burned in a power station it boils water into steam that spins a steam turbine that turns a generator to make electricity. Some power stations use natural gas in a gas turbine.

Natural gas is also converted into many different industrial chemicals. It is the most common feedstock for making pure hydrogen. Hydrogen is used as fuel in fuel cells, and to make ammonia. Ammonia is used as a fuel, as a fertilizer for crops, and for making many other things. Natural gas is also converted into monomers to make many plastic products.

## Related pages

- Fossil fuel
- Coal
- non-renewable resource

## Other websites

- History of using natural gas from the U.S. Department of Energy
Jewel

**Jewels** (or **gems** or **gemstones**) are rare minerals. They usually come in colours and sizes. They begin in a rough rock form, but can be cut and polished to turn into a jewellery.

However, some other non-mineral rocks (such as lapis lazuli) or organic materials can also be also used for jewelry and are called gemstones. These include amber or jet. Pearls and coral are sometimes also called gemstones.

Most gemstones are hard. Soft minerals are used in jewelry too, because of their luster that gives them value.

Being rare or in short supply also makes a gemstone valuable.

## History

The Ancient Greeks and Ancient Egyptians began to decide which gems are **Precious** and **semi-precious**. This continued in other cultures.::.

In modern times, the precious stones are diamond, ruby, sapphire and emerald, with all other gemstones being semi-precious.::.

## Types

- Amethyst
- Aquamarine
- Alexandrite
- Diamond
- Emerald
- Jade
- Peridot
- Ruby
- Sapphire
- Topaz
- Turquoise
- Opal
- Spinel

## Other websites

- "Book of Royal Gemstones" is a book from 1554 that talks about gemstones.
- "The Blossoms of Thoughts Regarding the Precious Stones" is an old book from the 1600s that is considered one of the most important books about precious stones. It is written in the Arabic language.
Xenon

**Xenon** is a non-metal chemical element. It has the chemical symbol **Xe** and atomic number 54.  As a noble gas, it is one of the few elements that are a gas at the standard temperature and pressure.

Sir William Ramsay and M. W. Travers discovered this element in 1898. The element's name came from the Greek word _xenos_, which means 'stranger'.

## Chemistry

Like other Noble gases, Xenon is very unreactive.  However, in 1962, chemists found that xenon can react with fluorine under special conditions, such as high pressure and high temperature. It is not known why xenon behaves differently under these circumstances. There are also some compounds with oxygen. The gas is not very reactive, because if fulfills the octet rule. This means that a lot of energy is needed to remove an electron from xenon. This activation energy for xenon is 1172 kJ/mol. To remove a second electron from xenon, an energy of 2046.4 kJ/mol is needed.

Known oxidation states of xenon are 0, +1, +2, +4, +6 and +8. However, the most stable form is pure xenon, or the xenon's oxidation state of 0. Xenon has 8 stable isotopes and more than 30 unstable isotopes.

## Uses

Xenon gas is used in electron tubes, bactericidal lamps, trobe lamps, and lamps used to excite ruby lasers.
It has the atomic mass of 131.294 and is the 5th inert gas in the inner gas group.

Xenon is also a trace gas in the atmosphere, occurring at 87 ±1 nL/L (parts per billion) or approximately 1 in 11.5 million. It is also emitted from some mineral springs.

## Related pages

- Periodic table
- List of common elements

## Infobox (xenon)
Denial

**Denial** is a word used in psychology on defense mechanism. It  means that someone denies that something has happened or is happening although he really knows it is true. Usually this happens because admitting it would cause a lot of pain. Denial is usually the first state of coping with losses.

## Examples

For instance, if someone close to a person dies, the survivor's first feeling might be denial, or refusal to accept the fact that the person is really dead. Denial, is also when you think that a team (like in football) will win a football match before its even started and refuse to accept the fact thet they could lose. Denial, is also when you refuse to accept the fact that someone else did something when you "think you know" it was a different person.

## Related pages

- Holocaust denial
- Holodomor denial
- Historical revisionism
- Rwandan genocide denial
- Cambodian genocide denial
Brass

**Brass** is an alloy of copper and zinc. Some types of brass are called bronzes.

Brass has a golden appearance. It is harder than pure metals and resists corrosion. It costs more than zinc.

There are some common brasses:
- Alpha brasses - with less than 40% zinc
- Beta brasses -
- White brasses - with more than 45% zinc

Things brass are used to make include:
- Brass instruments
- Ornaments
- Electrical fittings
- Buttons
- Screws
- Taps
- Hinges
- Door knobs

## Properties

Brass is more malleable than bronze or zinc. The melting point of brass can be 900 to 940 °C or 1,650 to 1,720 °F, depending on what it is made of. The density of brass is 8.4 to 8.73 g/cm<sup>3</sup> (0.303 to 0.315 lb/cu in).

Today, almost 90% of all brass alloys are recycled. Brass is not ferromagnetic. Brass scrap is collected and transported to the foundry. In the foundry, it is melted and recast into billets. The billets are heated and stretched into the form and size that is wanted.

Brass will corrode when it is exposed to moisture, chlorides, acetates, ammonia, and some acids.

## Brass alloys

There are many brass alloys. They include:

- Abyssinian gold
- Admiralty brass
- Aich's alloy
- Aluminum brass
- Arsenical brass
- Cartridge brass
- Common brass
- DZR brass
- Delta metal
- Free machining brass
- Gilding metal
- High brass
- Leaded brass
- Lead-free brass
- Low brass
- Manganese brass
- Muntz metal
- Naval brass
- Nickel brass
- Nordic gold
- Orichalcum
- Prince's metal
- Red brass
- Tombac
- Silicon tombac
- Tonval brass
- Yellow brass
Body

A **body** is the physical material of a person or organism. It is only used for organisms which are in one part or whole. There are organisms which change from single cells to whole organisms: for example, slime moulds. For them the term 'body' would mean the multicellular stage. Other uses:
- Plant body
- Cell body: here it may be used for cells like neurons which have long axons (nerve fibres). The cell body is the part with the nucleus in it.

The body of a dead person is also called a corpse or _cadaver_. The dead bodies of vertebrate animals and insects are sometimes called _carcasses_.

The human body has a head, neck, torso, two arms, two legs and the genitals of the groin, which differ between males and females.

The study of the body is anatomy.

The study of the workings of the body is physiology.

The word body is sometimes used in other ways.  For example, a lake is a body of water. The laws on a topic are a "body of law". An astronomy object is a "celestial body".

## Related pages

- Human body
Alloy

An **alloy** is a uniform mixture. It is made up of two or more chemical elements, of which at least one is a metal. An alloy has properties different from the metals it is made of.

Most alloys are made by melting the metals, mixing them while they are liquid to form a solution, then leaving them to cool and turn solid again.

## Theory

Combining a pure metal with one or more other metals or non-metals often makes it better. For example, steel is an alloy made from iron but it is stronger than iron. Physical properties like density, reactivity and electrical and thermal (heat) conductivity may not be much different than the elements (substances) which make the alloy. But, properties like strength can be very much different.

The first alloy to be discovered was Bronze. Bronze is made from copper and tin. Bronze was discovered a very long time ago in  the prehistoric period. Then, bronze was being used for making tools and weapons. This period was known as Bronze Age. But, later better alloys were discovered which replaced bronze for making tools and weapons. Now, bronze is used for making ornaments, statues, and bells. Brass is another alloy made from copper and zinc.

Melting point is the temperature at which a solid changes to liquid. Most alloys do not have a single melting point. They have a melting range in which the alloy is a mixture of solid and liquid stages. The temperature at which melting just starts is called solidus and the temperature at which the melting is just finished is called liquidus.

## Terms related to alloys

The term alloy means a mixture of atoms in which the main substance or the primary constituent is a metal. This primary metal is called the _base_ or _matrix_.

If an alloy has only two types of atoms, like copper-nickel alloy, then such an alloy is called _binary alloy_. If an alloy has three types of atoms, like iron, nickel and chromium, then it is called a _ternary alloy_. An alloy with four types of atoms is called a _quaternary alloy_ and an alloy with five types of atoms is called a _quinary alloy_.

Different varieties or forms of alloys can be made from the same constituent materials (substances from which the alloy is formed). These different forms or varieties can be formed by using different amounts of the constituents.

## Some common alloys

There are some common **alloys**:

- Brass is made of 35% zinc and 65% copper and is used for musical instruments, jewellery, faucets and decorative hardware.
- Stainless steel is mostly iron, plus more than 11% chromium, and various amounts of nickel and carbon and is used for tableware, cookware and surgical tools.
- Steel is made of 99% iron and 1% carbon and is used for tools, car bodies, machinery, girders and rails.
- Bronze is made of mostly copper and some tin and is used for boat hardware, screws and grill work.
- Alnico is a mix of aluminium, nickel and cobalt, and it is used to make permanent magnets.
- Amalgams are alloys of mercury with another metal, and are used in dental fillings.
- Electrum is a natural mix of gold and silver.
Material

**Material** is what everything that you can touch is made of. Even material that is too small to touch, is called material. We use materials to make things. We can also call material "physical substance<nowiki/>s."

_Raw_ material is materials such as ores which we can clean and mix with other materials to make another material like steel, for example. Cotton is a raw material used to make textile<nowiki/>s, which are used to make clothes. Material is not matter, though. Matter is everything in existence. Material is used for things that have use. Refined materials are materials that have been refined, like metal, reduced or converted into better, more useful materials like clothes and tools. Refined materials are usually mixes of other materials, like glue or steel.

## Some important materials

- Metals
    - Steel
    - Aluminum
    - Copper
    - Gold
- Polymers
    - Rubber
    - Plastic
- Ceramics
- Glass
- Cement
- Stone
- Textiles
    - Cotton fabric
    - Wool fabric
- organic materials
    - Leather
    - Bone
    - Paper
    - Lumber/wood
    - Glue
- Composites
    - Fiberglass
    - Concrete

## Table of material properties

|Material|Density (kg/m^3)|Young's Modulus (GPa)|Poisson's Ratio|Thermal Conductivity (W/m-K)|Specific Heat Capacity (J/kg-K)|Ref.|
| --- | --- | --- | --- | --- | --- | --- |
|Air|1.2|N/A|N/A|0.0262|1005||
|Aluminum|2700|69|0.33|237|910||
|Copper|8960|130|0.34|401|385||
|Glass (Pyrex)|2230|64|0.23|1.1|840||
|Gold|19320|79|0.44|320|129||
|Water|1000|N/A|N/A|0.606|4181||

## Related pages

- Materials science
Neuron

A **neuron** (or **neurone**) is a nerve cell that carries electrical impulses. Neurons are the basic units of our nervous system.

Neurons have a cell body (_soma_ or _cyton_), dendrites and an axon. Dendrites and axons are nerve fibers. There are about 86 billion neurons in the human brain. Almost all brain cells are neurons. The human brain has about 16 billion neurons in the cerebral cortex. The neurons are supported by glial cells and astrocytes.https://www.medicalnewstoday.com/articles/320289

Neurons are connected to one another, but they do not actually touch each other. Instead they have tiny gaps called synapses. These gaps are chemical synapses or electrical synapses which pass the signal from one neuron to the next.

Neuron ( link )https://www.medicalnewstoday.com/articles/320289

### By connection

There are three classes of neurons: motor neurons, sensory neurons and inter neurons.
- Sensory neurons carry information from tissues and organs into the central nervous system.
- Motor neurons transport signals from the central nervous system to the effector cells.
- Interneurons connect neurons within the central nervous system.

### By function

- Sensory neurons carry signals from sense organs to the spinal cord and brain.
- Relay neurons carry messages between sensory or motor neurons and the central nervous system
- Motor neurons carry signals from the CNS to muscles, motor neurons are connected to the relay neurons. The signal passes between the neurons via synapses. Synapses are microscopic voids between cells where chemicals are released from the axon terminal of one cell to specialized chemical receptors on the dendrite of the receiving cell.

## Cell division

Mature neurons never divide: that is the general rule. They do not undergo cell division. In most cases, neurons are generated by special types of stem cells. A type of glial cell, called astrocytes, have also been seen to turn into neurons. In humans, neurogenesis (the origin of new nerve cells) largely ceases during adulthood  but in two brain areas, the hippocampus and the olfactory bulb, there is strong evidence for substantial numbers of new neurons.

## Related pages

- Artificial neural network
- Brain cell
- Neurotransmitter

## Other websites

- Fibrinogen found to inhibit EGFR in neuronal cells  _Blood clotting protein may inhibit spinal cord regeneration_
- Cell Centered Database  UC San Diego images of neurons.
- High resolution neuroanatomical images of primate and non-primate brains .
Middle East

The **Middle East** is a large area of land in the eastern hemisphere. The lands of the Arabian Peninsula and some of the lands of the eastern Mediterranean are part of the Middle East. The Middle East's population is mostly Muslim. The name of the Middle East comes from its position to the east of Europe and to the west of the Far East.

The modern countries of Arabia (Saudi Arabia, Oman, Yemen, Bahrain, Jordan, Kuwait, and the United Arab Emirates) are usually counted with the modern countries of  Iraq, Syria, Lebanon, Cyprus, and Palestine (the State of Palestine and Israel) as part of the Middle East.

The name "Middle East" does not always have the same meaning, and the size of the area is not always the same. When the name Middle East started to be common, it was the name for the lands in between the Near East and the Far East. The Indian subcontinent was part of the Middle East at that time. Now, parts of south-west Asia and northern Africa can count as the Middle East. The land between Egypt and Iran is a common definition. Many countries in the Middle East today are also part of the Near East. Sometimes, people name countries that are far away from these countries as countries in the Middle East. These countries can be in North Africa (like Morocco) and the Indian subcontinent (like Pakistan). This area also has the name Greater Middle East.

Many ancient civilizations began in the Fertile Crescent in the Middle East. These were Sumer, Babylonia and Assyria in the area called Mesopotamia. The Abrahamic religions that believe in one God also originated in the Middle East. (Judaism and Christianity began in ancient Palestine and Islam began in Arabia.) Today, the Middle East is the homeland of Arabs, Turks, Persians, Kurds, and Jews, among many other ethnic groups. Islam is the most common religion in the Middle East.  Islam came from the Arabian Peninsula to most of the Middle East's lands in the 7th century AD, during the first Muslim conquests of the Sasanian Empire and parts of the Byzantine Empire. There are also significant historic Christian communities present in almost every Middle Eastern country. Other minority faiths include the Yazidis, Alevis, Druze and Alawites among others.

Today, the Middle East is very important because much of the petroleum that other countries use comes from here. There are also many arguments and wars, such as the conflict between Sunni and Shia, the Israeli–Palestinian conflict, and the Syrian civil war.

## Related pages

- Western Asia
- Central Asia
- East Asia
- South Asia
- Southeast Asia
- Levant
Hindu–Arabic numeral system

The **Hindu–Arabic numeral system**, sometimes known as the **Indo–Arabic numeral** or **Latin numeral system** or simply the **Hindu numeral system**, **Indo numeral system** or **Arabic numeral system**, is a system of numbers used all around the world. It is a base-ten place-value system. This system has ten basic lowercase-only symbols, which are 0, 1, 2, 3, 4, 5, 6, 7, 8 and 9. The Hindu–Arabic numeral system was first created by the Indians in the 6th century and used by the Arabs in the 7th century and Romans in the 16th century.

In Europe, Hindu-Arabic numeral system became very popular after the publication of _Liber Abaci,_ a book written by Italian mathematician Fibonacci. They are very different from previous methods of counting, such as the abacus. The numbers allowed mathematics to develop. In the past, many other number systems had been used.

## Infobox (infobox)

- **name**: Hindu–Arabic numeral system
- **title**: Hindu–Arabic numeral system
- **label1**: Base
- **data1**: Decimal (base 10)
- **label2**: Zero
- **data2**: 0
- **label3**: One
- **data3**: 1
- **label4**: Two
- **data4**: 2
- **label5**: Three
- **data5**: 3
- **label6**: Four
- **data6**: 4
- **label7**: Five
- **data7**: 5
- **label8**: Six
- **data8**: 6
- **label9**: Seven
- **data9**: 7
- **label10**: Eight
- **data10**: 8
- **label11**: Nine
- **data11**: 9
Point (geometry)

A **point** is a position in space which has no size, but which does have position.

In geometry, a point has no size, but has a position. This means it has no volume, area or length. We usually draw a point as a small cross 'X' or a small **dot** (a small, round shape). Different points can be labelled using capital letters (A, B, C...X, Y, Z). The point is one of the most fundamental ideas in geometry.

Two points form a line segment. When part of a line segment, the points are called its vertices. All polytopes are made of vertices.

In general, **two points** can be:
- Coincident (they are one and the same, such as on coinciding lines)
- Not coincident (they are not one and the same)
and are always:
- Coplanar (on the same plane)
- Colinear (on the same line)
- Concyclic (on the same circle)

**Three points** can be:
- Colinear
- Coincident
- Not coincident
- Not colinear
and are always:
- Coplanar
- Concyclic

**Four points** can be:
- Coplanar
- Colinear
- Coincident
- Not coincident
- Not colinear
- Not coplanar

## Related pages

- Line
- Plane
Line

A **line** is the path of one point that is moving. A line is a type of geometric figure. A line has length, but no width. A line is made up of an endless number of points.

## Straight and curved lines

A line can be straight or curved. In geometry, the word _line_ means a _straight line_. A straight line is the shortest distance between two points. A straight line is traced by a point moving in a direction that does not change.

A _curved line_ is sometimes called a curve. The edge of a circle is not straight. It is an example of a curve.

## Line segments

A _line segment_ is part of a line. Here are examples of straight line segments:

- <hr width="10%" height="5px" />
        - _____   __
        - <hr width="30%" height="5px" />

## Naming lines

Lines can get their names from any two points on the line. For example, if a line contains two different points, named  and , then the line can be called either , or .

Sometimes, lines are named with just one symbol. A letter such as  might be used.

## Two lines

Two lines can be:
- Parallel: Two lines are parallel if they are on the same plane and they never touch.
- Concurrent: Two lines are concurrent if they touch on one point.
- Coincident: Two lines are coincident if they are made of the same points.
- Perpendicular: Two lines are perpendicular if they make four right angles where they touch.
- Skew: In Euclidean space, two lines are skew if they are not parallel but they never touch.

## Related pages

- Linear function
- Point (geometry)
- Plane (mathematics)
Plane (mathematics)

A **plane** is a perfectly flat surface extending in all directions. It can be thought of as the ceiling of a room, only extended into all directions infinitely. A plane has two dimensions: length and width. All planes are flat surfaces. If a surface is not flat, it is called a _curved surface_.

The tool _plane_ can be used to create a flat, level surface like the mathematical plane—hence the name.

In geometry, a plane is made up of an infinite number of lines (or points). It has no depth. It is absolutely flat and infinitely large.

A _plane figure_ is part of a plane. It is named by the capital letters (such as A, B, C, ...X, Y, Z) that are put at its corners. Sometimes, a single capital pi  is also used to refer to a plane. A plane can also be named after three points that are not all on the same line.

In general, two planes can be:
- Parallel (they never meet)
- Concurrent (they meet forming a line)
- Coincident (they are one and the same)

## Plane in mathematics

In mathematics, a **plane** is a fundamental two-dimensional object. Intuitively, it looks like a flat infinite sheet of paper. There are several definitions of the plane. They are equivalent in the sense of Euclidean geometry, but they can be extended in different ways to define objects in other areas of mathematics. The only two-dimensional figure in our three-dimensional world is a shadow.

In some areas of mathematics, such as plane geometry or 2D computer graphics, the whole space in which the work is carried out is a single plane. In such situations, the definite article is used: _the plane_. Many fundamental tasks in geometry, trigonometry and graphing are performed in the two dimensional space, or in other words, in the plane.

## Euclidean geometry

A plane is a surface such that, given any three distinct points on the surface, the surface also contains all of the straight lines that pass through any two of them.
One can introduce a Cartesian coordinate system on a given plane in order to label every point on it with a unique ordered pair, which is composed of two numbers and is the coordinate of the point.

Within any Euclidean space, a plane is uniquely determined by any of the following combinations:

- Three points which are not lying on the same line
- A line and a point not on the line
- Two different lines which intersect
- Two different lines which are parallel
- A vector normal to the plane and a distance from the origin

## Related pages

- Point (geometry)
- Line

## Other websites

- Mathworld: Plane
- Easing the Difficulty of Arithmetic and Planar Geometry (work in Arabic, description in English)
Angle

When two straight lines come together, they make an **angle**. The two lines are called the _sides_ of the angle, and they meet at a point. A flat surface (called a plane) also forms an angle when it meets another.

To represent an angle, Greek letters such as  (alpha),  (beta),  (gamma) and  (theta) are sometimes used. An angle indicates the space between its sides, or the amount of rotation needed to make one side coincide the other.

To measure the size of an angle, we use units called degrees. A degree is a standard unit and we use the symbol ° after a number to show that it is a number of degrees. We can use a decimal number or a fraction for part of a degree, but a degree can also be divided into 60 minutes (1° = 60'), and a minute can be divided into 60 seconds (1' = 60"). So 22.5°, 22° and 22° 30' are all the same angle.

In mathematics, angles can also be (and often are) measured in radians instead of degrees, by using the conversion factor  (for example, ). Yet another unit of angle is gradian, with  .

Angles are studied in geometry, where an angle where edges meet is often called a vertex. For example, the three sides of a triangle are its _edges_ and two of the edges meet at each _vertex_. Similarly, two of the six sides (or _faces_) of a cube meet at each of its twelve edges, and three edges meet at each of its eight corners (or vertices, which is the plural version of _vertex_).

### Individual angles

- In a zero angle the lines lie one upon the other thus creating a 0° angle aka the zero angle.

- An angle measuring greater (wider) than 0° but less (narrower) than 90° is called an acute angle.

- An angle 90° wide is called a right angle.

- An angle more than 90° but less than 180° is called an obtuse angle.

- An angle that measures 180° is called a straight angle.
- An angle wider than 180° and narrower than 360° is called a reflex angle.
- An angle that has a made or full circle/completed 360° is called a full or complete angle.

### Special angle pairs

In geometry, there are pairs angles having a special relationship with each other, making them interesting and convenient.There is a pair of angles called complementary angles to which the sum of their measure (wideness) is equal to one right angle (which is equal to  turn, 90°, or  radians). Supplementary angles are also two angles, this time their combined measure is a straight angle ( turn, 180°, or  radians). Two angles that total to a full angle ( turn, 360°, or  radians) are referred to as _explementary_ or _conjugate_ angles.

## Related pages

- Sun angle
Lists of astronomical objects

This is a partial list of the various lists of astronomical objects which either exist, or should exist, in Wikipedia.

- List of planets
    - List of planetary moons
    - List of exoplanets
- Minor planets:
    - List of asteroids
    - List of comets
    - List of trans-Neptunian objects
        - List of trans-Neptunian objects by number
- List of stars
    - List of nearest stars
    - List of brightest stars
    - List of largest stars
    - List of smallest stars
    - List of stars with confirmed extrasolar planets
    - List of variable stars
    - List of semiregular variable stars
- special objects:
    - List of pulsars
    - List of quasars
    - List of blazars
    - List of gamma-ray bursters
    - List of black holes
        - List of largest black holes
- List of galaxies
    - List of nearest galaxies
    - List of farthest galaxies
- List of galaxy clusters
- List of cosmic structures
    - List of largest cosmic structures<sup>(en)</sup>
- List of satellites of the Milky Way
- List of traditional star names
- List of globular clusters
Beach

A **beach** is a landform along the coast of an ocean, sea, lake, or river. It usually consists of loose particles, such as sand, gravel, shingle, or pebbles. The particles of a beach are sometimes biological in origin, such as mollusc shells or bits of coral and sometimes bits of igneous rock, but the most common mineral in beaches is quartz.

Beaches are natural landing and launching places for boats, and landing craft are specially made for beaches.

People often use beaches for recreation. They swim, bask in the sun, or just relax. The most popular beaches have fine white or light-colored sand and warm water to swim in. Beaches are also used for diving or for seeing marine life.

Among the world's most popular and well-known beaches are Aruba (Dutch Caribbean), Long Beach (Canada), Copacabana Beach (Brazil), Hot Water Beach (New Zealand), Megan Bay (St. Thomas), Kailua Beach (Hawaii), Zandvoort Beach (Netherlands), Jeffreys Bay (South Africa), Bondi Beach (Australia) and Lake Como beaches (Italy).

Taking holidays on the beach is something of a British cultural export. Early railways in the 19th century took people to places they had never seen before. This tourism was made possible by the industrial revolution. Whole seaside resort towns grew to support visitors, where before there were just villages. Vacations at the sea became common all over the world.

Beaches are never static. They are always being built up or eroded, more quickly than other landforms. Over time the boundary between the land and the sea changes. New Romney, a small town in Kent, is one of the Cinque Ports, a 1.6 kilometres from the sea. In Henry VIII's time it was a port on the south coast of England. The growth of Dungeness has cut it off from the sea. Dungeness is a huge shingle beach.
Accident

An **accident** is when something goes wrong when it is not meant to. Physical accidents are things like collisions, injuries, and falling. Non-physical accidents are things like telling someone a secret without meaning to, forgetting something important, or deleting an important computer file.

Road accidents kill thousands of people each month in the United States, and thousands each week in the world. They injure more thousands each week. The majority involve a car but there are also many bus, truck and bicycle accidents. Aircraft crashes, ship sinkings and other transport accidents also attract much attention.

Injuries from accidents, however, are more numerous at home than elsewhere. They attract less attention because only a few people are hurt at a time.

Often, accidents are investigated so that we can learn how to avoid them in the future. Sometimes by studying an accident we can discover new things, for example penicillin.

Most of the deaths resulting from injuries are caused by fire accidents. Thus, accidental fires are one of the leading causes of unintentional deaths.  The main cause of death in fire incidents is burning, but inhalation of smoke and toxic gas causes death as well. Often the cause of the fire is very simple and unexpected, such as forgetting a candle near something flammable, defect in the hardware, or old electrical wires. So most of the large fires are caused by simple reasons.

## Work accidents

Industrial accidents such as mine cave-ins and the West Gate Bridge collapse also kill and maim many workers. The Bhopal disaster killed thousands, mostly not workers.

An accident at work is defined as an external, sudden and violent event. Work accidents happen while an someone is working. It may cause the injury or death of the worker or someone else.  For an accident to be a work accident, there must be a direct or indirect relationship of cause and effect between the accident and the work.

Many construction workers are injured.  There are multiple reasons for that, but the main  reason is working on the edge of high buildings without using a safety belt. Thus, you have to follow the safety rules when you are working on these places.

Chemical accidents can happen in a laboratory.  Especially, some students make chemical mistakes that injure them seriously.
Stone Age

The **Stone Age** was a prehistoric time when people made tools from stone such as flint. It began when people created the first stone tools about 3.3 million years ago. It lasted for about 3.4 million years, and ended between 4,000 BC and 2,000 BC. About 99% of human history happened during the Stone Age.

## Life

Stone Age people also made tools out of wood, antler, and bone. However, these materials do not last as long as stone. For this reason, most of the Stone Age tools archaeologists have found are made of stone.

Food eaten in the Stone Age included berries (e.g. blackberries), fish, animals (e.g. mammoth), and animal organs.

## Timeline

Archaeologists divide the Stone Age into three sections: Paleolithic ("old stone"), Mesolithic ("middle stone"), and Neolithic ("new stone"). During the Neolithic period, people invented farming and pottery, and started to care for animals like cows and pigs.

Sometime between 3000 BC and 2000 BC, people discovered the art of making metals. This probably happened in the Middle East. People used copper first, then learned how to make bronze. When people started using these metals instead of stone, the Stone Age ended and the Bronze Age began.

Some groups of people in Papua New Guinea continued to use Stone Age technology into the 20th century. They used stone-tipped weapons to kill animals for food and clothing. They made shelters using animal skin.
Virgil

**Publius Vergilius Maro** (; traditional dates 15 October 70 BC21 September 19 BC), usually called **Virgil** or **Vergil** ( ) in English, was a poet in the Latin language. His poems are about gods and their mythology.  Virgil's most famous epic poem is called the _Aeneid_.

## Life

Tradition is that Virgil was born in the village of Andes, near Mantua in Cisalpine Gaul. Scholars looking at the way he used words think that he may have Etruscan, Umbrian or even a Celtic background. Study of his name has led to beliefs that his family may have been earlier Roman settlers. These modern beliefs are not supported by evidence from his own writings or from writers of his biographies. Some scholars have noted that his nickname, _MARO_, is an anagram of the two main themes in the Aeneid: _AMOR_ (love) and _ROMA_ (Rome).
Alcohol (chemistry)

In chemistry, **alcohol** is a general term which refers to many organic compounds used in industry and science as reagents, solvents, and fuels. Common alcohols include rubbing alcohol, grain alcohol, wood alcohol, ethylene glycol, glycerin, and phenol.

Simple alcohols are made of an alkyl group with one or more hydroxyl () groups bound to its carbon atoms. They are often transparent colorless liquids.

## Names for alcohol

There are two ways of naming alcohols: Common names, and IUPAC names.

- Common names often are made by taking the name of the alkyl group, and adding the word "alcohol". For example, "methyl alcohol" or "ethyl alcohol".
- IUPAC names are made by taking the name of the alkane chain, removing the last "e", and adding "ol". Examples of this are "methanol" and "ethanol".

## Properties

The hydroxyl (OH) group makes alcohols polar, and they can form hydrogen bonds. Alcohols are weakly amphoteric, meaning they are both a weak acid and a weak base: they react with strong bases to make alkoxide anions, and strong acids to make oxonium cations.

Most alcohols are highly flammable.

## Common alcohols

The simplest two alcohols are methanol (or methyl alcohol) and ethanol (or ethyl alcohol), which have the following structures:

IUPAC nomenclature is used when describing more complex alcohols.

In common usage, "alcohol" often means ethanol or "grain alcohol". (See also: alcoholic proof).

Other commonly used alcohols include:
- Isopropyl alcohol (_sec_-propyl alcohol, propan-2-ol, 2-propanol) , or "rubbing alcohol"
- ethylene glycol (ethane-1,2-diol) , which is the main substance in antifreeze
- glycerin (or glycerol, propane-1,2,3-triol) , bound in natural fats and oils, which are triglycerides (esters of glycerol and fatty acids)
- phenol , an alcohol where the hydroxyl group is bound to a benzene ring.
The Holocaust

**The Holocaust** was the genocide of Jews in Europe by Nazi Germany, other Axis powers and their local collaborators in occupied territories between 1933 and 1945. At least 6,000,000 (six million) Jews (67% pre-war European Jews) were killed.

## Infobox (civilian attack)

- **title**: The Holocaust
- **partof**: World War II
- **image**: Selection on the ramp at Auschwitz-Birkenau, 1944 (Auschwitz Album) 1b.jpg
- **image size**: 240px
- **alt**: Large number of people standing beside a railway siding with the camp gate in the background
- **type**: Genocide, mass shooting, Death march, death marches, Deportation, mass deportation, mass murder by poison gas
- **motive**: Antisemitism
- **caption**: Jews arriving at Auschwitz concentration camp#Auschwitz II (Birkenau), Auschwitz II in The Holocaust in Nazi-occupied Poland, German-occupied Poland, May 1944. Most were selected to go to the gas chambers.
- **location**: Europe
- **date**: 1933–1945
- **fatalities**: At least 6,000,000 Jews
- **perps**: Nazi Germany, other Axis powers and local collaborators in occupied territories
Kyoto

**Kyoto** () is a city in Japan. This city was the capital of Japan from 794 until 1868.

Kyoto is a major city in the Kansai region of Japan. Its population is 1.5 million people. The city of Kyoto is the capital city of the prefecture of Kyoto. Kyoto is one of the cultural, educational, and technology centers of Japan. In it are many universities including Kyoto University, the second oldest national university of Japan.

## History

After 794, the Japanese emperors lived in this city which was called Heian-kyō.

In 1868, the city was called _Saikyō_ ("Western capital") in order to distinguish it from Edo (Tokyo) which was the "Eastern capital".

## Geography

There are mountains around the city on the east, north, and west sides. Some people in Kyoto believe that these mountains make Kyoto's summer especially hot and humid, and Kyoto's winter very cold.

We can see many temples and shrines built in traditional Japanese architectural styles here. Some of those buildings are registered as UNESCO World Heritage Sites. On the other hand, since Kyoto was one of biggest and richest Japanese cities in the middle of the 19th century; the citizens were eager to import European style, and there are many European style buildings in the center of Kyoto for company offices and schools.

Kyoto is one of oldest cities in Japan. Many tourists from all over the world come to Kyoto. Japanese people often come to Kyoto in the spring to see the cherry blossoms, and in the autumn to see the leaves change color.

Traditional Kyoto food often uses vegetables. McDonald's signboards in Kyoto are brown to preserve the traditional surroundings.

The oldest novel in the world, Shikibu Murasaki's The Tale of Genji is set in Kyoto during the Heian Period.

Kyoto is famous for three festivals: Gion festival, Aoi festival in the summer, and Jidai festival in the autumn.

## Related pages

- Kyoto Protocol
- Tokyo