Gross Domestic Income (GDI), also known as Gross Domestic Product (GDP) by income, is a measure of the total income generated within a country's borders in a given period of time, typically a year. GDI is calculated by adding up all the money earned by individuals, businesses, and the government in the country.

GDI is used as an economic indicator to measure the overall economic performance of a country. It is calculated by multiplying the total output of goods and services by their respective prices in the market. GDI takes into account all the production, consumption, and investment activities that take place within a country's borders, including foreign-owned businesses and citizens.

In addition to measuring the overall economic performance of a country, GDI is used by policymakers to make decisions about economic policies. A rising GDI indicates a healthy economy, while a decreasing GDI may suggest an economic slowdown or recession.

GDI is also used as a tool for international comparisons. This is because GDI provides a standardized measure that can be compared across different countries, allowing analysts to compare the economic performance of different countries. This information can be used to determine the relative levels of economic activity and growth between countries.