The first listed currency in the pair or the one to the left of the slash is called the base currency and the second currency or the one to the right of the slash is called the quote currency. In our example above the EUR is the base currency and the USD is the quote currency.
The bid price for each currency pair is the price which the dealer is willing to buy the base currency in exchange for the quote currency. This means the bid is the price which you will receive when you sell the currency pair. The ask price for each currency pair is the price which the dealer will sell the base currency in exchange for the quote currency. This means the ask price is the price you will pay when you buy the currency
The difference between the bid and ask price is commonly referred to as the spread.
A Forex