A country’s GDP (Gross Domestic Product) is one way of measuring the size of a nation’s economy. The GDP is the market value of all completed goods and services made by a nation over a set time period. The most common method of working out a nation’s GDP is by using this formula:
GDP = government spending + consumption + investment + (exports ? imports)
To see a list of countries and their GDP you have visit the GDP List
The GDP numbers have a big effect on the currency markets, infact it can be one of the biggest market moving reports. The GDP is taken into consideration by central banks when they make interest rate decisions. Higher than expected numbers can often improve a case for a rate hike and therefore increase the demand for the nation’s currency, the reverse is also true.