Globally, the 20th century was marked by: (a) two devastating world wars; (b) the Great Depression of the 1930s; (c) the end of vast colonial empires; (d) rapid advances in science and technology, from the first airplane flight at Kitty Hawk, North Carolina (US) to the landing on the moon; (e) the Cold War between the Western alliance and the Warsaw Pact nations; (f) a sharp rise in living standards in North America, Europe, and Japan; (g) increased concerns about the environment, including loss of forests, shortages of energy and water, the decline in biological diversity, and air pollution; (h) the onset of the AIDS epidemic; and (i) the ultimate emergence of the US as the only world superpower. The planet's population continues to explode: from 1 billion in 1820, to 2 billion in 1930, 3 billion in 1960, 4 billion in 1974, 5 billion in 1987, 6 billion in 1999, and 7 billion in 2012. For the 21st century, the continued exponential growth in science and technology raises both hopes (e.g., advances in medicine) and fears (e.g., development of even more lethal weapons of war).

The surface of the earth is approximately 70.9% water and 29.1% land. The former portion is divided into large water bodies termed oceans. The World Factbook recognizes and describes five oceans, which are in decreasing order of size: the Pacific Ocean, Atlantic Ocean, Indian Ocean, Southern Ocean, and Arctic Ocean.

The land portion is generally divided into several, large, discrete landmasses termed continents. Depending on the convention used, the number of continents can vary from five to seven. The most common classification recognizes seven, which are (from largest to smallest): Asia, Africa, North America, South America, Antarctica, Europe, and Australia. Asia and Europe are sometimes lumped together into a Eurasian continent resulting in six continents. Alternatively, North and South America are sometimes grouped as simply the Americas, resulting in a continent total of six (or five, if the Eurasia designation is used).

North America is commonly understood to include the island of Greenland, the isles of the Caribbean, and to extend south all the way to the Isthmus of Panama. The easternmost extent of Europe is generally defined as being the Ural Mountains and the Ural River; on the southeast the Caspian Sea; and on the south the Caucasus Mountains, the Black Sea, and the Mediterranean. Portions of Azerbaijan, Georgia, Kazakhstan, Russia, and Turkey fall within both Europe and Asia, but in every instance the larger section is in Asia. These countries are considered part of both continents. Armenia and Cyprus, which lie completely in Western Asia, are geopolitically European countries.

Asia usually incorporates all the islands of the Philippines, Malaysia, and Indonesia. The islands of the Pacific are often lumped with Australia into a "land mass" termed Oceania or Australasia. Africa's northeast extremity is frequently delimited at the Isthmus of Suez, but for geopolitical purposes, the Egyptian Sinai Peninsula is often included as part of Africa.

Although the above groupings are the most common, different continental dispositions are recognized or taught in certain parts of the world, with some arrangements more heavily based on cultural spheres rather than physical geographic considerations.

land area about 16 times the size of the US

the land boundaries in the world total 251,060 km (not counting shared boundaries twice); two nations, China and Russia, each border 14 other countries

a variety of situations exist, but in general, most countries make the following claims measured from the mean low-tide baseline as described in the 1982 UN Convention on the Law of the Sea: territorial sea - 12 nm, contiguous zone - 24 nm, and exclusive economic zone - 200 nm; additional zones provide for exploitation of continental shelf resources and an exclusive fishing zone; boundary situations with neighboring states prevent many countries from extending their fishing or economic zones to a full 200 nm

a wide equatorial band of hot and humid tropical climates - bordered north and south by subtropical temperate zones - that separate two large areas of cold and dry polar climates

the greatest ocean depth is the Mariana Trench at 10,924 m in the Pacific Ocean

the rapid depletion of nonrenewable mineral resources, the depletion of forest areas and wetlands, the extinction of animal and plant species, and the deterioration in air and water quality (especially in some countries of Eastern Europe, the former USSR, and China) pose serious long-term problems that governments and peoples are only beginning to address

3,245,566 sq km (2003)

large areas subject to severe weather (tropical cyclones); natural disasters (earthquakes, landslides, tsunamis, volcanic eruptions)

large areas subject to overpopulation, industrial disasters, pollution (air, water, acid rain, toxic substances), loss of vegetation (overgrazing, deforestation, desertification), loss of wildlife, soil degradation, soil depletion, erosion; global warming becoming a greater concern

the world is now thought to be about 4.55 billion years old, just about one-third of the 13.75-billion-year age estimated for the universe

Mandarin Chinese 12.44%, Spanish 4.85%, English 4.83%, Arabic 3.25%, Hindi 2.68%, Bengali 2.66%, Portuguese 2.62%, Russian 2.12%, Japanese 1.8%, Standard German 1.33%, Javanese 1.25% (2009 est.)

Christian 33.35% (of which Roman Catholic 16.83%, Protestant 6.08%, Orthodox 4.03%, Anglican 1.26%), Muslim 22.43%, Hindu 13.78%, Buddhist 7.13%, Sikh 0.36%, Jewish 0.21%, Baha'i 0.11%, other religions 11.17%, non-religious 9.42%, atheists 2.04% (2009 est.)

7,021,836,029 (July 2012 est.)

19.14 births/1,000 population

7.99 deaths/1,000 population

2.47 children born/woman (2012 est.)

2.94 beds/1,000 population (2005)

33.3 million (2009 est.)

1.8 million (2009 est.)

195 countries, 72 dependent areas and other entities

the legal systems of nearly all countries are generally modeled upon elements of five main types: civil law (including French law, the Napoleonic Code, Roman law, Roman-Dutch law, and Spanish law); common law (including United States law); customary law; mixed or pluralistic law; and religious law (including Islamic law); an additional type of legal system - international law - governs the conduct of independent nations in their relationships with one another

all members of the UN are parties to the statute that established the International Court of Justice (ICJ) or World Court; 55 countries have accepted jurisdiction of the ICJ with reservations and 11 countries have accepted ICJ jurisdiction without reservations; states parties to the Rome Statute of the International Criminal Court (ICCt) are those countries that have ratified or acceded to the Rome Statute, the treaty that established the Court; a total of 121 (effective 1 July 2012) countries have accepted jurisdiction of the ICCt (see Appendix B for a clarification on the differing mandates of the ICJ and ICCt)

In 2011, world output - and per capita income - continued to recover from the 2008-09 recession, the first global downturn since 1946. Gross World Product (GWP) grew 3.7%, a slowdown from the 5.2% rate achieved in 2010. Growth was unevenly distributed: lower income countries - those with per capita incomes below $30,000 per year - averaged 4.1% growth, while higher income countries - with per capita incomes above $30,000 - averaged 2.2% growth. Among large economies, China (+9.2%), Argentina (+8.9%), India (+7.2%), Nigeria (+7.2%), and Saudi Arabia (+6.8%) recorded the biggest GDP gains - although all were off the pace they set in 2010. Continuing uncertainties in financial markets slowed growth in Spain (+0.7%), Italy (+0.4%), and Greece (-6.9%), while the tsunami and Fukushima nuclear disaster hit Japan (-0.7%). Growth fell below 2% in both the US and the European Union, in part because of growing concern among consumers and investors about the size of government debt and its impact on the direction of fiscal policy. In 2011, global unemployment continued to creep upwards, reaching 9.0% - underemployment, especially in the developing world, remained much higher. Global gross fixed investment was a bright spot, jumping almost two percentage points to 24.8% of GWP, after a significant drop in 2009; direct investment across international borders climbed 7%. World trade grew 18% in 2011, but the pre-2009 pattern of surplus and deficit countries has returned. With the growth of international trade and investment, world external debt rose nearly 7%, reversing a 5% decline in 2010. Many, if not most, countries pursued expansionary monetary and fiscal policies, although at a reduced pace from 2010. The global money supply, narrowly defined, rose 7%, and broadly defined money increased roughly 8%, as central banks continued efforts to keep interest rates low. The global budget deficit was narrowed to roughly $3 trillion - 4.2% of World GDP, as governments tried to rein in spending and slow the rise of public debt.

The international financial crisis of 2008-09 has presented the world economy with a major new challenge, together with several long-standing ones. The fiscal stimulus packages put in place in 2009-11 required most countries to run budget deficits. Treasuries issued new public debt - totaling $6.5 trillion since 2008 - to pay for the additional expenditures. To keep interest rates low, many central banks monetized that debt, injecting large sums of money into the economies. When economic activity picks up, central banks will face the difficult task of containing inflation without raising interest rates so high they snuff out further growth. At the same time, governments will face the difficult task of spurring current growth and employment without saddling their economies with so much debt that they sacrifice long-term growth and financial stability.

Long-standing challenges the world faces are several. The addition of 80 million people each year to an already overcrowded globe is exacerbating the problems of underemployment, pollution, waste-disposal, epidemics, water-shortages, famine, over-fishing of oceans, deforestation, desertification, and depletion of non-renewable resources. The nation-state, as a bedrock economic-political institution, is steadily losing control over international flows of people, goods, funds, and technology. Internally, central governments often find their control over resources slipping as separatist regional movements - typically based on ethnicity - gain momentum, e.g., in many of the successor states of the former Soviet Union, in the former Yugoslavia, in India, in Iraq, in Indonesia, and in Canada. Externally, central governments are losing decisionmaking powers to international bodies, most notably the EU. The introduction of the euro as the common currency of much of Western Europe in January 1999, while paving the way for an integrated economic powerhouse, poses economic risks because the participating nations are culturally and politically diverse and have varying levels and rates of growth of income, and hence, differing needs for monetary and fiscal policies. In Western Europe, governments face the difficult political problem of channeling resources away from welfare programs in order to increase investment and strengthen incentives to seek employment. Because of their own internal problems and priorities, the industrialized countries devote insufficient resources to deal effectively with the poorer areas of the world, which, at least from an economic point of view, are becoming further marginalized. The terrorist attacks on the US on 11 September 2001 accentuated a growing risk to global prosperity, illustrated, for example, by the reallocation of resources away from investment to anti-terrorist programs. Wars in Iraq and Afghanistan added new uncertainties to global economic prospects.

Despite these challenges, the world economy also shows great promise. Technology has made possible further advances in all fields, from agriculture, to medicine, alternative energy, metallurgy, and transportation. Improved global communications have greatly reduced the costs of international trade, helping the world gain from the international division of labor, raise living standards, and reduce income disparities among nations. Much of the resilience of the world economy in the aftermath of the financial crisis has resulted from government and central bank leaders around the globe working in concert to stem the financial onslaught, knowing well the lessons of past economic failures.

$80.33 trillion (2011 est.)

$77.46 trillion (2010 est.)

$73.65 trillion (2009 est.)

GWP (gross world product): $69.99 trillion (2011 est.)

3.264 billion (2011 est.)

24.8% of GDP (2011 est.)

23% of GDP (2010 est.)

28.9% of GDP (2011 est.)

-4% of GDP (2011 est.)

64.1% of GDP (2011 est.)

62.7% of GDP (2010 est.)

world average 5% (2011 est.)

developed countries 3% (2011 est.)

developing countries 6.3% (2011 est.)

$25.64 trillion (31 December 2011 est.)

$23.88 trillion (31 December 2010 est.)

$81.61 trillion (31 December 2011 est.)

$75.57 trillion (31 December 2010 est.)

$110.3 trillion (31 December 2011)

$100.4 trillion (31 December 2010)

$47.01 trillion (31 December 2011)

$56.36 trillion (31 December 2010)

$48.69 trillion (31 December 2009 est.)

dominated by the onrush of technology, especially in computers, robotics, telecommunications, and medicines and medical equipment; most of these advances take place in OECD nations; only a small portion of non-OECD countries have succeeded in rapidly adjusting to these technological forces; the accelerated development of new industrial (and agricultural) technology is complicating already grim environmental problems

$17.97 trillion (2011 est.)

$15.18 trillion (2010 est.)

the whole range of industrial and agricultural goods and services

$17.82 trillion (2011 est.)

$14.96 trillion (2010 est.)

the whole range of industrial and agricultural goods and services

$69.08 trillion (31 December 2011 est.)

$62.5 trillion (31 December 2010 est.)

$19.38 trillion (31 December 2011)

$17.88 trillion (31 December 2010)

$20.63 trillion (31 December 2011)

$19.32 trillion (31 December 2010)

20.68 trillion kWh (2009 est.)

19.01 trillion kWh (2009 est.)

596.6 billion kWh (2010 est.)

668.9 billion kWh (2010 est.)

4.821 billion kW (2009 est.)

66.6% of total installed capacity (2009 est.)

7.9% of total installed capacity (2009 est.)

18.5% of total installed capacity (2009 est.)

4.9% of total installed capacity (2009 est.)

84.82 million bbl/day (2011 est.)

40.22 million bbl/day (2009 est.)

41.79 million bbl/day (2009 est.)

1.526 trillion bbl (1 January 2012 est.)

79.97 million bbl/day (2008 est.)

88.02 million bbl/day (2011 est.)

22.67 million bbl/day (2008 est.)

21.02 million bbl/day (2008 est.)

3.359 trillion cu m (2010 est.)

3.314 trillion cu m (2010 est.)

1.098 trillion cu m (2010 est.)

1.446 trillion cu m (2010 est.)

191.3 trillion cu m (1 January 2011 est.)

31.78 billion Mt (2010 est.)

total airports - 43,794 (2012)

the International Maritime Bureau (IMB) reports that 2011 saw a very slight (1%) decrease in global pirate activities with marginally fewer people taken hostage at sea; in 2011, pirates attacked a total of 439 ships world-wide including hijacking 45 ships, capturing 802 seafarers, and killing eight; while the Horn of Africa remains the most dangerous area for maritime shipping, accounting for more than 50% of all attacks in 2011, a number of attacks also occurred in the coastal waters of Indonesia, the South China Sea, Bangladesh, and West Africa; as of July 2012, there have been 189 attacks worldwide with 20 hijackings; the Horn of Africa remains the most dangerous region in 2012 with 70 attacks, 13 hijackings, 212 hostages seized; as of July 2012, Somali pirates hold 11 vessels and 174 hostages; the decrease in successful pirate attacks is due, in part, to more aggressive anti-piracy operations by international naval forces as well as the increased use of armed security teams aboard merchant ships

roughly 2% of GDP of gross world product (2005 est.)

stretching over 250,000 km, the world's 322 international land boundaries separate 195 independent states and 71 dependencies, areas of special sovereignty, and other miscellaneous entities; ethnicity, culture, race, religion, and language have divided states into separate political entities as much as history, physical terrain, political fiat, or conquest, resulting in sometimes arbitrary and imposed boundaries; most maritime states have claimed limits that include territorial seas and exclusive economic zones; overlapping limits due to adjacent or opposite coasts create the potential for 430 bilateral maritime boundaries of which 209 have agreements that include contiguous and non-contiguous segments; boundary, borderland/resource, and territorial disputes vary in intensity from managed or dormant to violent or militarized; undemarcated, indefinite, porous, and unmanaged boundaries tend to encourage illegal cross-border activities, uncontrolled migration, and confrontation; territorial disputes may evolve from historical and/or cultural claims, or they may be brought on by resource competition; ethnic and cultural clashes continue to be responsible for much of the territorial fragmentation and internal displacement of the estimated 6.6 million people and cross-border displacements of 8.6 million refugees around the world as of early 2006; just over one million refugees were repatriated in the same period; other sources of contention include access to water and mineral (especially hydrocarbon) resources, fisheries, and arable land; armed conflict prevails not so much between the uniformed armed forces of independent states as between stateless armed entities that detract from the sustenance and welfare of local populations, leaving the community of nations to cope with resultant refugees, hunger, disease, impoverishment, and environmental degradation

the United Nations High Commissioner for Refugees (UNHCR) estimated in June 2011 that there were 43.7 million people forcibly displaced worldwide; this includes 15.1 million refugees and as many as 27.5 million IDPs in more than 40 countries (2011)