In currency exchange, there is always one currency that is bought and one that is sold (the sold currency is used to purchase the bought currency). The currencies bought and sold are determined by two things in the order form. First, whether the "buy" or "sell" button on the order form is selected, and second, which currency pair is selected. If you want to buy or sell the second currency in a pair (the quote currency), you have to think backwards, since the "buy" button will actually sell the quote currency in exchange for the base currency and the "sell" button will buy the quote currency using the base currency. Below is a summary:
- If the "buy" button is selected and currency pair X/Y is selected, then currency X will be bought and currency Y sold.
- If the "sell" button is selected and currency pair x/y is selected, then currency X will be sold and currency Y will be bought.
If you have funded your account with US Dollars (USD) and wish to acquire Bitcoin (BTC), you can do so by placing a new buy order using the BTC/USD currency pairing. This will exchange your USD for BTC according to the details of your order.
Image: order form when placing a new buy order on the BTC/USD market
Now, if you are holding Bitcoin Cash (BCH) on your account and wish to acquire more Bitcoin (BTC), you can do so by placing a new sell order using the BCH/BTC currency pairing. This will exchange your BCH for BTC according to the details of your order.
Image: order form when placing a new sell order on the BCH/BTC market