how does a currency lose or gain value
Currency appreciation and depreciation 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, having to do with trade flows, 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.
Inflation In economics, inflation is a sustained increase in the general price level of goods and services in an economy over a period of time.[1] When the price level rises, each unit of currency buys fewer goods and services; consequently, inflation reflects a reduction in the purchasing power per unit of money – a loss of real value in the medium of exchange and unit of account within the economy.[2][3] A chief measure of price inflation is the inflation rate, the annualized percentage change in a general price index, usually the consumer price index, over time.[4] The opposite of inflation is deflation.