instruction: What is a Gross domestic product (GDP)?
output: Gross domestic product (GDP) is a monetary measure of the market value of all the final goods and services produced and sold in a specific time period by a country or countries, generally "without double counting the intermediate goods and services used up to produce them". GDP is most often used by the government of a single country to measure its economic health. Due to its complex and subjective nature, this measure is often revised before being considered a reliable indicator. GDP (nominal) per capita does not, however, reflect differences in the cost of living and the inflation rates of the countries; therefore, using a basis of GDP per capita at purchasing power parity (PPP) may be more useful when comparing living standards between nations, while nominal GDP is more useful comparing national economies on the international market. Total GDP can also be broken down into the contribution of each industry or sector of the economy. The ratio of GDP to the total population of the region is the per capita GDP (also called the Mean Standard of Living).