National income means total income of the economy as a whole. National income is a measure of the economic performance of an economy. According to the national income estimation committee of 1951, national income measures the volume of commodities ans services produced during a given period counted without duplication.

Following are the four basic concepts of National Income. They are

GDP - Gross Domestic Product
NDP - Net Domestic Product
GNP - Gross National Product
NNP - Net National Product
PCI - Per Capita Income

Gross Domestic Product

GDP is the money value of final goods and services produced in the domestic territory of a country during an accounting year GDP does not include income earned from abroad.

NDP is net domestic product which is the sum total of money value of final goods and services produced in the country in an accounting year excluding depreciation cost.

GNP - Gross National Product or Gross National Income is the total measure of the flow of goods and services at market value resulting from current production in a year including Net Factor Income Earned from Abroad (NFYEA).

NNP - It is the sum total of money value of final goods and services produced in an accounting year excluding depreciation cost. NNP includes Net Factor Income Earned From Abroad. Net National Product at factor cost is also known as National Income.

Per capita income

Per Capita Income refers to the income per head of the people of a country. It is obtained by dividing the National Income by the population of a country.

Per capita income = National Income / Population

So the key economic indicators are National income and Per capita Income