A region's gross domestic product,or GDP,is one of the ways for measuring the size of its economy.The GDP of a country is defined as the market value of all final goods and services produced within a country in a given period of time.It is also considered the sum of value added at every stage of production of all final goods and services produced within a country in a given period of time.Until the 1980s the term GNP or gross national product was used in the United States.The two terms GDP and GNP are almost identical - and yet entirely different; GDP being concerned with the region in which income is generated and GNP (or GNI - Gross National Income) being a measure of the accrual of income to a region.The most common approach to measuring and understanding GDP is the expenditure method:
GDP = consumption + investment + (government spending) + (exports − imports)