Macroeconomics studies large-scale economic decisions. For example, a whole country's economy (or, its economic output) is summarised by the GDP (gross domestic product). Many governments use macroeconomic ideas to decide how much tax to collect and what interest rates should be.

It also considers the amount of unemployment, the rate that prices go up (inflation), and the exchange rates of its currency. The exchange rate affects the amount of imports and exports. Exchange rates and taxation are "levers of the economy".