It is the first currency quoted in a currency pair on forex. It is also typically considered the domestic currency or accounting currency. For accounting purposes, a firm may use the base currency to represent all profits and losses. For example, if you are looking at the CAD/USD currency pair, the Canadian dollar would be the base currency and the U.S. dollar would be the quote currency. The price represents how much of the quote currency is needed for you to get one unit of the base currency.

The first currency stated in a currency pair.

In a currency exchange, the exchange rate is quoted as the units of one currency in terms of a single unit of a base currency.