The base currency is the first currency in any currency pair.
It shows how much the base currency is worth as measured
against the second currency. For example, if the USD/CHF
rate equals 1.6215, then one USD is worth CHF 1.6215.
In the FOREX markets, the U.S. Dollar is normally considered
the “base” currency for quotes, meaning that quotes are expressed
as a unit of $1 USD per the other currency quoted in the pair.
The primary exceptions to this rule are the
British Pound, the Euro, and the Australian Dollar.