Two prices, not one
When you look at a market, you see two prices: the bid and the ask. The bid is the price at which you can sell, and the ask (sometimes called the offer) is the price at which you can buy. The ask is always slightly higher than the bid.
Many beginners see a single number on a simplified display and are surprised that buying and selling happen at different prices. Understanding the bid-ask pair is essential to understanding what your trade actually costs.
The spread is your starting cost
The gap between the bid and the ask is the spread, and it is one of the main ways brokers earn from your trading. Because you buy at the higher ask and would sell at the lower bid, every trade begins fractionally in the red — you must recover the spread before you are even breaking even.
A concrete example: if a pair shows a bid of 1.1000 and an ask of 1.1002, the spread is two points. Buy at 1.1002 and the market must rise to 1.1002 on the bid side before you profit — the price literally has to move in your favour just to erase the spread.
Why the spread size matters
A tight spread lowers the hurdle every trade must clear; a wide one raises it. This is why liquid major pairs with small spreads are friendlier to frequent trading than exotic pairs with wide ones. For a scalper making many trades, spread is the dominant cost.
Spreads are not fixed. They widen when liquidity thins — around news, at market opens, and during shocks. Watching how the spread on your instrument behaves through the day teaches you a lot about when it is cheap or expensive to trade.