GDP is used worldwide to measure the economic health of a country. Economists use GDP figures to figure out whether a country's economy is in recession, depression or boom. Countries that have higher GDPs generally have access to better health and education facilities, for instance. Richer countries can afford to spend more on research and development.
Though a country's GDP is usually calculated by its respective statistical agency, most countries follow established international standards while calculating. As GDP is calculated in the currency of the respective country, while comparing the GDP of the two countries, the usual method followed is converting the currencies of the two countries into US dollars.