Transfer payments (Social Security, welfare) are redistributions, not purchases of goods/services. They become consumption when recipients spend them. Counting both would double-count.

Directly, yes—negative NX subtracts from GDP. But imports satisfy demand that would otherwise require domestic production. The composition changes, not necessarily the level.

Gross private domestic investment: business equipment, structures, residential construction, and inventory changes. NOT financial investments like stocks—those are asset transfers, not production.

GDP measures production, not welfare. It ignores inequality, environmental costs, and unpaid work. Use alongside other measures (HDI, median income) for fuller picture.

Expenditure sums what buyers spend (C+I+G+NX). Income sums what producers earn—wages, profits, rents, interest, plus taxes less subsidies and depreciation. In theory both equal GDP; in practice BEA reports a small 'statistical discrepancy' between them.

Americans consume and invest more than they produce, financed by net foreign capital inflows. The dollar's reserve-currency status keeps it strong, which makes imports cheap and exports relatively expensive, so the trade balance has been negative since the mid-1970s.

Nominal GDP uses current prices, so it rises with inflation. Real GDP fixes prices to a base year (BEA uses chained 2017 dollars) to isolate volume changes. Use real GDP for growth comparisons; use nominal GDP for ratios like debt-to-GDP.

The production approach sums value added across industries (gross output minus intermediate inputs), giving a sector-by-sector view that expenditure and income totals hide. All three approaches estimate the same GDP from different data sources, which helps cross-check the headline figure.