Gross domestic product
Components of GDP by expenditure

GDP (Y) is the sum of consumption (C), investment (I), government Expenditures (G) and net exports (X − M).

Here is a description of each GDP component:

C, I, and G are expenditures on final goods and services; expenditures on intermediate goods and services do not count. (Intermediate goods and services are those used by businesses to produce other goods and services within the accounting year.) So for example if a car manufacturer buys auto parts, assembles the car and sells it, only the final car sold is counted towards the GDP. Meanwhile, if a person buys replacement auto parts to install them on their car, those are counted towards the GDP.

According to the U.S. Bureau of Economic Analysis, which is responsible for calculating the national accounts in the United States, "In general, the source data for the expenditures components are considered more reliable than those for the income components."

Encyclopedia Britannica records an alternate way of measuring exports minus imports: notating it as the single variable NX.
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