How is GDP of a country calculated?

[Good-Person]

The term "GDP" is called "Gross Domestic product". It is usually calculated by analysing the imports and experts of a country. This also accounts for total revenue generated by a country through other means as well, so how is it calculated?

 

[Nomad]

Gross Domestic Products is the total national income of the country, it does not include imports because it is not an income, however, customs clearance and customs duty are included in GDP. GDP includes total exports as well as the total internal income of the country.