If you are a forex trader, you should know that every forex broker are quotes two different prices for a currency pair, where one of them called a bid price, and the other is an asking price. When you sell your base currency, it's called the bid price. On the other hand, ask the price when you buy your base currency by trading. So, what is spread? in these two prices, the difference is called the Spread in forex trading. Some peoples also called it a bid/ask spread.