The economic growth of a country is measured by the growth of its Gross Domestic Product (GDP), which is a measure of national income. GDP is the total market value of all final products the domestic economy produces. The value of the GDP has not been deducted by depreciation on capital goods (capital) used in production activity, so it is called gross. Another measure that is also widely used is Gross National Product (GNP). Unlike GDP, GNP is not based on where the products are produced but on the nationality of the producers of the products. There is a guideline about the recording and calculation mechanism of national income, known as the System of National Accounts (SNA).
There are three approaches to calculating national income, namely from the production, expenditure, and income sides. From the production side, GDP is calculated from the added value generated by the economy by aggregating the added value of all business sectors. From the expenditure side, GDP is calculated based on the expenditure of economic agents, namely expenditure on consumption, investment, and export-import. Meanwhile, from the income side, GDP is calculated based on the income received by the owners of the factors of production, namely wages and salaries received by labour and business surplus or profit earned by owners of firms. Based on SNA, the three approaches to calculating national income produce the same value of GDP, and because of that, the three approaches can be reconciled.