Gross domestic product (GDP) is a measure of the size of an economy. It is defined as "an aggregate measure of production equal to the sum of the gross values added of all resident, institutional units engaged in production (plus any taxes, and minus any subsidies, on products not included in the value of their outputs) are commonly used to measure the economic performance of a whole country or region, but can also measure the relative contribution of an industry sector. The more familiar use of GDP estimates is to calculate the growth of the economy from year to year , The pattern of GDP growth is held to indicate the success or failure of economic policy and to determine whether an economy is 'in recession'.