Devaluation
Devaluation only applies to pegged currencies. A government or central bank announces a new, lower peg — suppose the official rate shifts from 7 units per dollar to 10 units per dollar. Overnight, the domestic currency buys fewer dollars. This is a policy choice, not a market outcome, which is what distinguishes it from depreciation.
Why would a government devalue? Most commonly, to restore export competitiveness. If a currency has been held artificially strong — perhaps because defending the old peg drained foreign-exchange reserves — devaluing aligns the official rate closer to where the market would naturally price it. It can also relieve the pressure of a currency crisis by removing the incentive for speculators to bet against the peg.
The costs are significant. Imports become more expensive immediately, raising prices for consumers and businesses that rely on foreign inputs — this feeds into inflation. Debt denominated in foreign currency becomes harder to service because it now costs more domestic currency to buy each dollar of repayment. Historically, devaluations in emerging markets have often triggered sharp rises in consumer prices and economic disruption. Economists track these effects through inflation and trade indicators.
A common confusion: devaluation is sometimes used loosely to describe any currency weakening, but technically it refers only to a formal reset of a fixed rate. A freely floating currency cannot be "devalued" — it can only depreciate. The distinction matters because devaluation reflects a deliberate political decision with immediate, system-wide consequences.