The gross domestic product (GDP) or gross domestic income (GDI) is one of the measures of national income and output for a given country’s economy. GDP is defined as the total market value of all final goods and services produced within the country in a given period of time (usually a calendar year). It is also considered the sum of value added at every stage of production (the intermediate stages) of all final goods and services produced within a country in a given period of time, and it is given a money value.

Expenditure approach

The most common approach to measuring and understanding GDP is the expenditure method:

GDP = consumption + gross investment + government spending + (exports − imports), or,
GDP = C + I + G + (X-M)

“Gross” means depreciation of capital stock is not subtracted. If net investment (which is gross investment minus depreciation) is substituted for gross investment in the equation above, then the formula for net domestic product is obtained.

The components of GDP

Each of the variables C, I, G and XM (where GDP = C + I + G + (X-M) as above)

• C is private consumption in the economy. This includes most personal expenditures of households such as food, rent, medical expenses and so on but does not include new housing.
• I is defined as investments by business or households in capital. Examples of investment by a business include construction of a new mine, purchase of software, or purchase of machinery and equipment for a factory. Spending by households on new houses is also included in Investment. In contrast to its colloquial meaning, ‘Investment’ in GDP does not mean purchases of financial products. Buying financial products is classed as ’saving’, as opposed to investment. The distinction is (in theory) clear: if money is converted into goods or services, it is investment; but, if you buy a bond or a share of stock, this transfer payment is excluded from the GDP sum. That is because the stocks and bonds affect the financial capital which in turn affects the production and sales which in turn affects the investments. So stocks and bonds indirectly affect the GDP. Although such purchases would be called investments in normal speech, from the total-economy point of view, this is simply swapping of deeds, and not part of real production or the GDP formula.
• G is the sum of government expenditures on final goods and services. It includes salaries of public servants, purchase of weapons for the military, and any investment expenditure by a government. It does not include any transfer payments, such as social security or unemployment benefits.
• X is gross exports. GDP captures the amount a country produces, including goods and services produced for other nations’ consumption, therefore exports are added.
• M is gross imports. Imports are subtracted since imported goods will be included in the terms G, I, or C, and must be deducted to avoid counting foreign supply as domestic.

* source of this article is wikipedia

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