National is the sum of wages (and other labor compensation), rent, interest, and profits.

The statement you've provided describes the concept of "National Income." National Income is an aggregate measure that includes the total income earned by a nation's residents in the production of goods and services. It encompasses various forms of income, including:

1. Wages and Salaries: This represents the compensation paid to employees for their labor.
2. Rent: This is the income earned from the rental of properties or land.
3. Interest: This is the earnings from investments, such as savings accounts or bonds.
4. Profits: This refers to the residual income that remains after all expenses have been deducted from revenue in business.

National income is crucial for assessing the overall economic performance of a country and is used as a key indicator of economic health. It can be calculated using various approaches, such as the production approach, income approach, or expenditure approach, each providing insight into different aspects of the economy. Understanding national income is essential for policymakers, economists, and business leaders as it affects decisions related to economic policy, investment, and resource allocation.