Currency

What Is a Currency?

A currency is the system of money a country or group of countries uses to buy goods and services, pay debts, and measure value. It can exist as physical coins and banknotes or as electronic balances held in bank accounts. Each currency has an official name and a standard three-letter code. For example, the U.S. dollar is commonly written as USD, and the euro as EUR.

Currency performs three main functions. It is a medium of exchange, so people accept it in payment. It is a unit of account, so prices and contracts are stated in it. It is also a store of value, so people can save it and expect it to hold its purchasing power over time.

How Currency Works

Most modern currencies are fiat money, which means they have value because the government declares them legal tender and people accept them, rather than because they are exchangeable for a fixed amount of a precious metal. In most countries a central bank issues and manages the currency. It uses tools such as interest rates to influence inflation, which is the general rise in prices over time.

Currencies trade against one another in the foreign exchange market. The price of one currency in terms of another is the exchange rate. Exchange rates move in response to factors such as interest rate differences, trade flows, economic growth, and investor sentiment.

Why Currency Matters to Investors

Currency affects investors in several ways. An investment priced in a foreign currency can gain or lose value when that currency moves against the investor's home currency, even if the underlying asset's price does not change. A company that earns much of its revenue abroad may report results that shift with exchange rates. Investors refer to this exposure as currency risk. Some governments and institutions hold certain currencies as a reserve currency, which can influence how widely those currencies are used and how they behave in global markets.

Understanding currency helps investors read international returns more accurately. Returns in a foreign market should be considered in both the local currency and the investor's own currency.