The difference between a country's total value of exports and imports - a surplus means exports exceed imports, a deficit means the reverse.
The trade balance is a component of the current account and one of the longer-term structural drivers of currency valuation. A persistent trade surplus (exports > imports) generates sustained demand for the exporting country's currency: foreign buyers must purchase the currency to pay for goods. Japan's structural current account surplus is one reason the yen tends to attract safe-haven inflows even when Japan's own interest rates are near zero.
Conversely, a persistent trade deficit means the country must finance imports with capital inflows - foreign investment in its bonds, equities, or real estate. The US runs a large trade deficit that is financed by the dollar's reserve currency status and deep capital markets. If confidence in those inflows deteriorates, the deficit is negative for the currency.
Market-moving trade data includes the US monthly Trade Balance release (typically 5–6 weeks after the reference month) and the Chinese trade balance, which affects commodity currencies (AUD, NZD, CAD) because China is a dominant buyer of raw materials. The deviation from consensus and any revision to the prior month's figure drives the immediate forex reaction.
Exchange rates themselves feed back into the trade balance: a weaker currency makes exports cheaper for foreign buyers (stimulating export revenue) and makes imports more expensive for domestic consumers (reducing import volume). This self-correcting mechanism - called the J-curve effect - means a depreciation initially worsens the nominal trade deficit (existing contracts keep paying at old prices) before improving it as quantities adjust over 6–18 months.