Gross domestic product of countries in the world

The Gross domestic product (or GDP) refers to the monetary value of all the finished goods and servives produced within a country´s borders in
a specific time period, though GPD is usually calculated on an annual basis. It includes all of private and public consumption, government outlays, investments and exports less imports that occur within a defined territory.
To calculate the GDP in a place:

                                                       GDP = C+G+I+NX

Where:
"C" is equal to all private consumption, or consumer spending, in a nation's economy
"G" is the sum of government spending
"I" is the sum of all the country's businesses spending on capital
"NX" is the nation's total net exports, calculated as total exports minus total imports. (NX = Exports - Imports).

Here you´ve got a list of the largest economies by nominal GDP, 2011: