National income: 

National income refers to the total net value of all goods and services produced within a nation over a specified period of time, representing the sum of wages, profits, rents, interest, and pension payments to residents of the nation. National income is considered a major economic indicator that helps the study of overall economic activity, production, consumption and trade in a country. National income measures the money value of the flow of output of goods and services produced within an economy over a period of time. Measuring the level and rate of growth of national income is important to economists when they are considering the rate of economic growth, changes over time to the average living standards of the population, changes over time to the distribution of income between different groups within the population (that is, measuring the scale of income and wealth inequalities within society.

A country's national income provides useful information about: 

• The overall size of the country's economy.
• Economic growth trends in comparison to the previous year's performance and the nation's economic health.
• The contribution of various production sectors to the national economy.
• Future growth prospects.
• Standard of living in the country 

National income data also helps the government strategize future economic policies and formulate developmental plans. It also helps business groups estimate future market trends in terms of product demand. To measure how much output, spending and income has been generated in a given time period national income accounts can be used. Basically, these accounts measure three things: 

• Output: i.e., the total value of the output of goods and services produced in the UK.
• Spending: i.e., the total amount of expenditure taking place in the economy.
• Incomes: i.e., the total income generated through production of goods and services