The World Bank annually classifies world countries based on their Gross Domestic Product (GDP). Gross Domestic Product (GDP) is the market value of a country's production of goods and services during a time period, usually a quarter or a year. The World Bank Group is a specialized United Nations organism whose declared mission is to reduce poverty by granting low interest loans, loans without interest to other banks, and economic aid to developing countries. It was created in 1944 and its headquarters are in Washington D.C. (USA). It is currently comprised of 185 member countries.