User:Zach Vega/GDP draft

Gross domestic product (GDP) is the market value of all final goods and services from a nation in a given year. Countries are sorted by nominal GDP estimates from financial and statistical institutions, which are calculated at market or government official exchange rates.

Several economies which are not considered to be countries (world, international unions, and some dependent territories) are included in the lists because they appear in the sources. These economies are italicized and not ranked in the charts, but are listed where applicable.

The figures presented here do not take into account differences in the cost of living in different countries, and the results can vary greatly from one year to another based on fluctuations in the exchange rates of the country's currency. Such fluctuations may change a country's ranking from one year to the next, even though they often make little or no difference to the standard of living of its population. Therefore these figures should be used with caution.

Some countries/regions may have citizens which are on average wealthy. These countries/regions could appear in this list as having a small GDP. This would be because the country/region listed has a small population, and therefore small total economy; the GDP is calculated as the population times market value of the goods and services produced per person in the country.

Comparisons of national wealth are also frequently made on the basis of purchasing power parity (PPP), to adjust for differences in the cost of living in different countries. PPP largely removes the exchange rate problem, but has its own drawbacks; it does not reflect the value of economic output in international trade, and it also requires more estimation than nominal GDP. On the whole, PPP per capita figures are more narrowly spread than nominal GDP per capita figures.

The United States is the world's largest national economy with a GDP of approximately $16.8 trillion, due to high average incomes, a large population, capital investment, moderate unemployment, high consumer spending, a relatively young population, and technological innovation. Tuvalu is the world's smallest national economy with a GDP of about $40 million because of a lack of natural resources, reliance on foreign aid, negligible capital investment, demographic problems, and low average incomes.

The first list includes data compiled by the United Nations Statistics Division for 2012, the second list largely includes data (estimate) compiled by the International Monetary Fund's World Economic Outlook for 2013, the third list shows the World Bank's mostly 2012 estimates, and the fourth list includes mostly 2012 estimates from the The World Factbook by the Central Intelligence Agency.