GDP is defined as the total value of goods and services produced within a territory during a specified period . GDP measures only final goods and services, that is those goods and services that are consumed by their final user, and not used as an input into other goods.
The most common approach to measuring and understanding GDP is the expenditure method:
Expenditure approach - Total expenditures on all finished goods and services produced within the economy. Calculation: GDP using the expenditure approach is derived as the sum of all final expenditures, changes in inventories and exports of goods and services less imports of goods and services.