GDP

Gross Domestic Product is the total value of all goods and services produced within a country's borders over a specific period (usually a quarter or year). It is THE single most important number for measuring the size and health of an economy.

US GDP is approximately $29 trillion annually, making it the world's largest economy. GDP growth of 2-3% is considered healthy. Below 0% for two consecutive quarters is the simplified definition of a recession (the official definition from NBER is more nuanced).

Components of GDP (C + I + G + NX):
• Consumer spending (C): ~68% of US GDP - the biggest driver by far
• Business investment (I): ~18% - equipment, R&D, construction
• Government spending (G): ~17% - federal, state, local
• Net exports (NX): ~-3% - the US imports more than it exports

GDP has limitations: it doesn't measure income inequality, environmental costs, unpaid work, or quality of life. A country can have high GDP but terrible living standards if wealth is concentrated.