Why when choosing a Forex broker https://adrofx.com low spreads is the thing to look for? Spread in Forex trading is the difference between the bid and ask values. The bid is the exchange rate that applies to a trader during a purchase and ask is the price quote of the chosen currency. Bid is always lower than ask and the size of the difference between them is called a spread. For a broker this is a way to apply transaction fees to the traders.