National Income:
National income is the total value of all goods and services produced within a country's borders in a specific time period. It is an important indicator of a country's economic health and is used to measure the overall economic activity of a nation.

Interrelationship between Product, Value Added Income Generation, and Expenditure Method:
- Product Method: The product method of calculating national income involves summing up the value of all goods and services produced in an economy. It includes the value of all final goods and services produced in different sectors of the economy.
- Value Added Income Generation: Value added is the difference between the value of goods and services produced and the cost of inputs used in production. It represents the contribution of each sector to the overall national income. By summing up the value added at each stage of production, we can arrive at the total national income.
- Expenditure Method: The expenditure method calculates national income by summing up all expenditures made on final goods and services in an economy. It includes consumption expenditure, investment expenditure, government expenditure, and net exports.
The interrelationship between these methods lies in the fact that they all contribute to the calculation of national income. The product method focuses on the value of production, the value added income generation method focuses on the contributions of different sectors, and the expenditure method focuses on the total expenditures made in the economy. By combining these methods, we can get a comprehensive picture of an economy's overall economic activity and national income.