Income refers to the collection of natural or legal fruits of property. The right to income can also be obtained by the non-owner in accordance with the law or with the consent of the owner. Income from production and operation, operating income and benefits.

The concept of economics. Historically, the concept of income first appeared in economics.

In The Wealth of Nations, Adam Smith defined income as "the amount that can be consumed without eroding capital" and regarded income as the increase of wealth. Later, most economists inherited and developed this view. 1890, AlfredMaarshell introduced Adam Smith's income view of "increasing wealth" into enterprises in Principles of Economics, and put forward the idea of economic income to distinguish material capital from value-added income.

At the beginning of 20th century, irving fisher, a famous American economist, developed the theory of economic benefits. In his book The Essence of Capital and Income, firstly, the concept of income is analyzed from the manifestation of income, and three different income forms are put forward.

(1) spiritual gain-spiritual satisfaction;

(2) Real income-the increase of material wealth;

3) Monetary gains-increase the monetary value of assets. In the above three different forms of income, there are both measurable and unmeasurable. Among them, spiritual income is too subjective to be measured, while monetary income is easy to be measured without considering the static concept of currency change. Therefore, economists only focus on real income.