Currency depreciation is the loss of value of a country's currency with respect to one or more foreign reference currencies, typically in a floating exchange rate system in which no official currency value is maintained.Currency appreciation in the same context is an increase in the value of the currency. Short-term changes in the value of a currency are reflected in changes in the exchange rate.
In a floating exchange rate system, a currency's value goes up (or down) if the demand for it goes up more (or less) than the supply does. In the short run this can happen unpredictably for a variety of reasons, including the balance of trade, speculation, or other factors in the international capital market. For example, a surge in purchases of foreign goods by home country residents will cause a surge in demand for foreign currency with which to pay for those goods, causing a depreciation of the home currency.
Another cause of appreciation (or depreciation) of a currency is speculative movements of funds in the belief that a currency is under- (or over-)valued and in anticipation of a "correction". Such movements may in themselves cause the value of a currency to change.
A longer-run trend of appreciation (or depreciation) is likely to be caused by home country inflation being lower (or higher) on average than inflation in other countries, according to the principle of long-run purchasing power parity.
When a country's currency appreciates in relation to foreign currencies, foreign goods become cheaper in the domestic market and there is overall downward pressure on domestic prices. In contrast, the prices of domestic goods paid by foreigners go up, which tends to decrease foreign demand for domestic products.
A depreciation of the home currency has the opposite effects. Thus, depreciation of a currency tends to increase a country's balance of trade (exports minus imports) by improving the competitiveness of domestic goods in foreign markets while making foreign goods less competitive in the domestic market by becoming more expensive.
In the international capital market, a change in a currency's value may give rise to a foreign exchange gain or loss. The appreciation of the domestic currency raises the value of financial instruments denominated in that currency, while there is an adverse impact on debt instruments.