Purchasing Power Parity (PPP) is a method of calculating exchange rates that allows for comparison of economic productivity and standards of living between countries. It is based on the theory that a currency's purchasing power should be the same in every country; therefore, the exchange rate should be the one that would equalize the prices of an identical basket of goods and services in any two countries. Various international organizations, like the World Bank and IMF, regularly publish estimates of GDP based on PPP, and India has consistently ranked among the top economies by this measure, often in the top 5 or 6.