When making trades on an exchange, you are provided a price listing for each listed pair. However, when you want to place a buy or sell order, the price for your order may differ from the listed price. This difference, or the bid-ask spread, is the difference between the prices listed and those for immediate sale or purchase. More precisely, it is the highest price another buyer is willing to pay (their bid) and the lowest price another seller is accepting (their ask). If you are a seller you will see the bid price, while a buyer will see the ask price. A seller must decide if they are willing to accept the difference in their own asking price and the available bid price. The same is true for a buyer;he/she must decide if they are willing to pay more.
On Amplify Exchange, our brokerage services enable users to trade at the best prices available under an umbrella of multiple crypto exchanges. For more details about this and the bid-ask spread, click this link.