is the planet earth viewed especially as the home of human beings and other living things.
The earth is just one of countless heavenly bodies in the universe. But it is the only one
known to support life.
From the very beginning of their life on the earth, people have had to adapt to conditions
in the world to survive. The earliest human beings lived by hunting and gathering wild
plants. They made clothing from animal hides and furs and used branches and other natural
materials to build shelters. About 10,000 years ago, some people began to raise plants and
animals after food became scarce. People who farmed could settle in one place and produce
enough food to feed many others. Villages grew up, and people developed methods of living
in large groups. New occupations and forms of government became necessary. Over the years,
people created more advanced technology and increasingly complicated forms of social life.
They built great cities, developed civilizations, and found ways to control many powerful
The world's surface consists of water and land. Air
surrounds the surface and extends to outer space. Water--chiefly the great oceans--covers
about 70 percent of the world's surface. All living things must have water to live, just
as they must have air. People also use water for irrigation, industry, power, and
transportation. In addition, the oceans, lakes, and rivers provide fish and other foods.
The oceans separate huge land masses called continents. Most of the world's countries lie
on the continents. Others are on islands. Each country has its own political and economic
systems. However, countries cooperate with one another in many ways. For example, they
make trade agreements and sign treaties designed to reduce the likelihood of war.
The physical features of a country strongly influence where the people of that country
live. People can most easily grow food on plains or in river valleys, where the soil is
rich and deep. Mountainous regions generally are not suitable for crop farming because the
soil is thin and easily washed away by rainfall. Many of the world's biggest cities began
as important trading centers on seacoasts, lakeshores, and riverbanks. Thus, the majority
of the world's people live on flat, fertile plains and in large cities that border major
water transportation routes.
About 6 billion people live in the world. They are distributed unevenly over the land.
Many areas are heavily populated. Other areas have no people at all. The population is
increasing far more rapidly in some countries than in others.
All the world's people belong to the same species, Homo sapiens, which means they have a
common ancestry. But many groups of people have lived apart for such a long time that they
have developed certain physical variations.
In the past, scholars used physical variations to classify people into races. The members
of one race were thought to resemble one another more than they resembled the members of
other races. Today, most anthropologists (scientists who study human beings) reject the
idea that human beings can be biologically classified into races. However, people in
numerous societies continue to view themselves and others as members of various races. See
Physical differences among people have often been confused with cultural differences, such
as differences in language or religion. Physical and cultural differences have been a
basis of discrimination and prejudice. At times, these differences have served as an
excuse for slavery, violence, and war.
This article provides an overview of the world as the home of human beings. It briefly
describes the world's nations, people, and surface features. See also the Related articles
listed at the end of this article.
Nations of the world
The world has 192 independent countries and about 40 dependencies. An independent country
controls its own affairs. Dependencies are controlled in some way by independent
countries. In most cases, an independent country is responsible for the dependency's
foreign relations and defense, and some of the dependency's local affairs. However, many
dependencies have complete control of their local affairs.
Almost all of the world's people live in independent countries. Only about 10 million
people live in dependencies.
The world's largest nation in area is Russia. It covers 6,592,850 square miles (17,075,400
square kilometers). The next four largest nations--Canada, China, the United States, and
Brazil--each cover more than 3 million square miles (8 million square kilometers).
The five smallest independent countries in the world, in descending order, are San Marino,
Tuvalu, Nauru, Monaco, and Vatican City. Each of these countries covers less than 25
square miles (65 square kilometers). Vatican City has an area of only 1/6 square mile (0.4
Throughout history, the political map of the world has changed repeatedly. The most
important changes have resulted from major wars. During ancient times, such military
leaders as Alexander the Great and Julius Caesar conquered many different groups of people
and established vast empires. Numerous empires rose and fell during later periods of
history, and boundaries changed again and again.
Beginning about 1500, many European nations established colonies in North America, South
America, Asia, Africa, and Australia. Most national boundaries established by the ruling
countries remained after the colonies gained their independence.
World War I (1914-1918) and World War II (1939-1945) resulted in many important changes on
the world map. World War I led to the formation of a number of new nations in Europe,
including Austria, Czechoslovakia, Hungary, and Yugoslavia. After World War II, several
nations gained or lost territory. In addition, many new nations were established in Asia.
In Africa, an independence movement swept the continent. More than 45 African colonies
gained their independence in the middle and late 1900's. In 1991, the Soviet Union broke
apart into Russia and 14 other independent nations.
How nations are grouped. The nations of the world may be grouped in various ways. They may
be grouped by region, such as the Middle East and Central America. People often call the
countries of the Eastern Hemisphere the Old World and those of the Western Hemisphere the
New World. In addition, countries are often identified by continent, such as African or
Economists generally divide the nations of the world into two groups--developed nations
and developing nations. Developed nations have a wide variety of industries and, in
general, are wealthier than developing nations. Developing nations have long depended on
agriculture and have few industries. Most of them are poor.
Developed nations include the United States, Canada, Japan, Australia, and most countries
in Western Europe. More than 120 countries are considered to be developing nations. The
majority are in Africa, Asia, and Latin America. Most industrial nations lie in the
Forms of government. Nearly all governments claim to be democracies. However, governments
differ greatly in how closely they fulfill the democratic ideal of government by the
people. In a democracy, the people elect representatives. These representatives make laws
and govern the people according to those laws. The people may run for office and remove
officials who behave improperly. Nations and governments can be classified as being more
or less democratic, depending on the extent to which the people may take part in the
process of government.
Democratic nations may be republics or constitutional monarchies. For example, the United
States is a republic in which the president serves as head of state and head of
government. The United Kingdom is a constitutional monarchy. A king or queen serves as
head of state, and a prime minister serves as head of government. Other countries with
democratic governments include Canada, Australia, New Zealand, Japan, and most countries
of Western Europe.
Many countries that claim to be democracies actually have an authoritarian government. In
such countries, relatively few people have power, and most citizens play a limited role in
making decisions. Authoritarian governments may rule by persuasion, force, or both.
Communist Party organizations control authoritarian governments in China and a few other
nations. Dictators supported by the army rule other countries.
Economic systems. Every country has an economic system to determine how to use its
resources. The three main economic systems today are (1) capitalism, (2) Communism, and
(3) mixed economies.
Capitalism is based on free enterprise--that is, most of the resources needed for
production are privately owned. Individuals and private firms determine what to produce
and sell, and how to use their income. Capitalism is practiced in the United States,
Canada, Australia, New Zealand, and many countries of Western Europe.
Communism traditionally has been based on government ownership of most productive
resources. The government also plays a large role in deciding what goods to produce and
how to distribute income. Communism was once the main economic system in the Soviet Union
and many nations of Eastern Europe. However, these nations began to decrease government
control over their economies in the late 1980's and early 1990's. Today, few countries
claim to run their economies on Communist principles. Even China and other countries that
are often thought of as Communist have loosened control over economic activities.
Mixed economies combine both private control and government control. Under a mixed
economy, the government may own such industries as banks, railroads, and steel. However,
other industries are privately owned. The government does some economic planning, but it
also allows much private choice. Norway, Sweden, Denmark, and certain Latin American
countries have mixed economies.
Cooperation among nations. Every nation depends on other nations in some ways. The
interdependence of the entire world and its peoples is called globalism. Nations trade
with one another to earn money and to obtain manufactured goods or the natural resources
that they lack. Nations with similar interests and political beliefs may pledge to support
one another in case of war. Developed countries provide developing nations with financial
aid and technical assistance. Such aid strengthens trade as well as defense ties.
Several international organizations promote cooperation among countries. The United
Nations (UN) is the largest such organization. Nearly all independent countries are UN
members. The UN works mainly to settle disputes among nations and to maintain world peace.
It also has programs to aid needy people and to improve health and education, particularly
in developing nations.
Many international organizations are designed to encourage economic progress among member
nations. Such groups stimulate trade among members by eliminating tariffs and other trade
barriers within the organization. These groups include the European Union, the European
Free Trade Association (EFTA), and the Central American Common Market.
People of the world
Population. By 2000, the world's population surpassed 6 billion. The yearly rate of
population growth is about 1.4 percent. At that rate, the world's population would double
in about 49 years.
If all the world's people were distributed evenly over the land, over 100 people would
live on every square mile (40 on every square kilometer). However, the world's people are
not distributed evenly, and so the population density (the average number of people in a
specific area) varies greatly. Some regions, including Antarctica and certain desert
areas, have no permanent settlers at all.
The most densely populated regions of the world are in Europe and in southern and eastern
Asia. North America has heavy concentrations of people in the northeastern and central
regions and along the Pacific coast. Africa, Australia, and South America have densely
populated areas near the coasts. The interiors of those continents are thinly settled.
Just as the population density varies from one part of the world to another, so does the
rate of population growth. Developing countries generally have higher average rates of
increase than developed nations. Africa has a population growth rate of 2.5 percent
yearly, the highest of all continents. South America has a 1.7 percent rate of increase,
and Asia a 1.5 percent rate. Australia's rate of increase is 0.7 percent, and North
America's rate is 0.6 percent. Europe's population is actually declining, losing 0.1
percent each year.
The world's largest country in terms of population is China, which has more than a billion
people. India ranks second largest, followed in descending order by the United States,
Indonesia, Brazil, Russia, and Pakistan. Over half the world's people live in these seven
nations. Vatican City has the smallest population of any of the world's nations. It has
only about 1,000 people.
The growth and change of the world's population throughout history are described in the
article POPULATION. See also the articles on individual countries, states, and provinces
for population details.
Languages. There are about 3,000 spoken languages in the world. However, only 12 are
widely used. Each of these languages is spoken by over 100 million people. More people
speak English than any other language. Mandarin Chinese ranks second, followed by Spanish,
Hindi, Arabic, Bengali, Russian, Portuguese, Japanese, German, Malay-Indonesian, and
Beginning in the 1500's, England, Spain, Portugal, and France established colonies in
various parts of the world. For this reason, English, Spanish, Portuguese, and French are
now spoken in many nations outside their countries of origin. English became the chief
language of such nations as the United States, Australia, and New Zealand. It is also one
of the main languages in Canada and South Africa. Spanish became the chief language
throughout most countries of Latin America. Portuguese became the main language of Brazil,
Mozambique, and Angola.
French, like English, is an important language of Canada. Most people in the province of
Quebec speak French. French is also widely spoken in Algeria, Chad and some other
countries in western Africa, Morocco, and Vietnam.
For information about the development of the world's languages, see LANGUAGE. See also the
articles on individual countries for the most widely used languages in those nations.
Religions. The peoples of the world practice thousands of religions, but only eight
religions have followers that number in the millions. Christianity has about 11/2 billion
members, more than any other religion. Islam has more than 500 million members. The six
other major religions are Buddhism, Confucianism, Hinduism, Shinto, Taoism, and Judaism.
Christianity originated in the Middle East. Today, most Christians live in Europe and
North and South America. Islam also began in the Middle East and is now the chief religion
throughout most of the area. It is also the major faith in northern Africa, Malaysia,
Indonesia, Pakistan, and Bangladesh. Hinduism has most of its followers in India, where
the religion originated. Buddhism, which also developed in India, is the major religion of
Sri Lanka and the mainland of southeastern Asia. Buddhism also has many followers in such
countries as Japan and South Korea. Shinto is the native religion of Japan.
Confucianism and Taoism are native religions of China. The Communist government of China
discourages them and all other religions. However, Chinese people living in Taiwan still
practice Confucianism and Taoism. Judaism originated in the Middle East. Today, the
largest number of Jews live in the United States, Israel, France, and Russia. Thousands of
local traditional religions are practiced by ethnic groups in Africa, Asia, Australia,
North America, South America, and the Pacific Islands.
For a description of the major religions, see RELIGION and the separate articles on the
various faiths. See also the Religion section of the country and continent articles.
Problems among the world's people. Through the years, human beings have made great
progress in providing for their basic needs. Modern methods of producing food, clothing,
and shelter have helped many people live more comfortably. Education has become available
to more and more people, and scientists have discovered cures for many diseases.
But serious problems still face the world's people. Millions of people in developing
countries lack adequate food, clothing, shelter, medical care, and education. Many people
in developed countries, especially in large cities, suffer from poverty, unemployment, and
discrimination. New problems have also developed. Numerous nations face the growing
problem of environmental pollution.
Physical features of the world
The surface area of the world totals about 196,800,000 square miles (509,400,000 square
kilometers). Water covers about 138,800,000 square miles (359,200,000 square kilometers),
or 71 percent of the world's surface. Only 29 percent of the world's surface consists of
land, which covers about 58,000,000 square miles (150,202,000 square kilometers).
The physical geography of a specific region includes the region's surface features and
climate. It also includes the soil, mineral deposits, plant and animal life, and other
natural resources. Physical geography thus helps determine the economy of a region and how
people in the region live.
This section describes the two major surface features of the world: (1) water and (2)
Water. Oceans, lakes, and rivers make up most of the water that covers the surface of the
world. The water surface consists chiefly of three large oceans--the Pacific, the
Atlantic, and the Indian. The Pacific Ocean is the largest. It covers about 70 million
square miles (181 million square kilometers), or about a third of the world's surface. The
Atlantic Ocean is about half as large as the Pacific, and the Indian Ocean is slightly
smaller than the Atlantic. These three oceans come together around Antarctica. The
Atlantic Ocean and the Pacific Ocean meet again near the North Pole, where they form the
The world's largest lake is the Caspian Sea, a body of salt water that lies between Asia
and Europe east of the Caucasus Mountains. The Caspian covers about 143,250 square miles
(371,000 square kilometers). The world's largest body of fresh water is the Great Lakes in
North America. These five lakes--Erie, Huron, Michigan, Ontario, and Superior--are
interconnected, and so they can be referred to as one body of water. Together, they cover
94,230 square miles (244,060 square kilometers).
The longest river in the world is the Nile in Africa, which flows 4,145 miles (6,671
kilometers). The second longest river, the Amazon in South America, has a length of 4,000
miles (6,437 kilometers). The Missouri is the longest river in the United States. It flows
2,540 miles (4,090 kilometers).
All living things need water to stay alive. People obtain drinking water from rivers,
freshwater lakes, and wells. We also require water for our way of life. We use water in
our homes for cleaning and cooking. The manufacture of almost all our products requires
water. In dry regions, farmers draw water from rivers, lakes, and wells to irrigate crops.
Oceans, lakes, and rivers supply us with fish and other foods.
Water is also a source of power. The force of falling water from rivers, waterfalls, and
dams can be used to generate hydroelectricity. In such countries as Brazil and Norway,
hydroelectric power stations supply nearly all the electricity used in industry and homes.
The waters of the world also serve as major transportation routes. Every day, thousands of
cargo ships cross the oceans, sail along seacoasts, and travel on inland waters. A
nation's location along a seacoast can have a powerful influence on its progress and
prosperity. The United States, Great Britain, Japan, and some other leading trading
nations have long coastlines. Many of the world's major cities border important water
Land. The land area of the world consists of seven continents and many thousands of
islands. Asia is the largest continent, followed by Africa, North America, South America,
Antarctica, Europe, and Australia. Geographers sometimes refer to Europe and Asia as one
continent called Eurasia.
The world's land surface includes mountains, plateaus, hills, valleys, and plains.
Relatively few people live in mountainous areas or on high plateaus. Most such regions are
too cold, rugged, or dry for comfortable living or for crop farming and other human
activities. The soil is poor and easily washed away by rain. However, some mountain
valleys and high grassy plateaus serve as grazing land for cattle, sheep, and other
livestock. The majority of the world's people live on plains or in hilly regions. Most
plains and hilly regions have excellent soil and an abundant water supply. They are good
regions for farming, manufacturing, and trade. Many areas unsuitable for farming,
particularly mountainous regions, have plentiful mineral resources. Some desert areas,
especially in the Middle East, have large deposits of petroleum.
A region's natural resources influence its economic development. The Pampa, a grassy plain
in central Argentina, has excellent pastureland for raising cattle and rich soil for
growing wheat. Beef and wheat make up Argentina's leading exports. Britain lacks enough
good farmland to support all its people, but large deposits of coal and iron ore helped
make the country an industrial power. Such countries as Canada, Russia, and the United
States have a variety and abundance of natural resources, which have greatly helped their
Threats to the environment. For centuries, people have used the world's natural resources
to make their lives more comfortable. However, these resources are not always used wisely.
Many problems have thus resulted that threaten the environment.
Many water supplies have become polluted by sewage, industrial chemicals, and other
wastes. The burning of fuel in motor vehicles, factories, and furnaces has caused air
pollution in numerous cities. Forest regions have been stripped of large areas of trees,
resulting in soil erosion and the destruction of animal life. Certain farming practices,
including the use of chemical fertilizers and pesticides, have polluted the soil. Many
farmers plant the same crop in a field year after year, which reduces the soil's
Since the mid-1900's, people have become increasingly aware of the need to protect their
environment. Local and national governments have passed laws to control the use of natural
resources. But it takes many years to renew a water supply, grow a forest, or replace a
layer of topsoil. People must practice conservation continuously to repair damage that has
already occurred and to prevent future problems.