Spread is the gap between the price a trader can buy at and the price a trader can sell at. It is one of the first trading costs a beginner sees. Wider spread means the trade starts further behind, and it can affect entries, exits, stop placement, and short-term strategies.
Basics
If EUR/USD shows a bid of 1.1000 and an ask of 1.1002, the spread is 2 pips. A buy order starts from the ask price, so price must move enough to cover that 2-pip cost before the trade is actually ahead. During news or low-liquidity hours, spread can widen and make a clean setup less attractive.