How do we measure the product in an economy?

In an economy, product measurement is primarily done through Gross Domestic Product (GDP), which quantifies the total value of all goods and services produced over a specific period. GDP can be measured using three approaches: the production approach, which calculates output; the income approach, which sums incomes earned by factors of production; and the expenditure approach, which aggregates consumption, investment, government spending, and net exports. Additionally, indicators like Gross National Product (GNP) and Net National Product (NNP) offer alternative perspectives on economic performance.