This document discusses concepts related to measuring gross domestic product (GDP). It defines GDP as the total market value of all final goods and services produced within a country in a given period. GDP is calculated using both the expenditure approach, which sums consumer spending, investment, government spending, and net exports, and the income approach, which sums compensation to workers, business profits, interest, rent, and taxes. The document also distinguishes between nominal GDP measured in current prices and real GDP adjusted for inflation using a price deflator. It notes limitations to using fixed weights from a base year to calculate real GDP.