Order Book

An order book is the live list of all outstanding buy and sell orders for a trading pair on an exchange, organized by price. Buy orders (bids) sit below the current price and sell orders (asks) sit above it, each showing how much of the asset traders are willing to buy or sell at that level. When a bid and an ask meet at the same price, a trade executes and both orders are filled.

For example, the order book for BTC/USDT might show a bid of 2 BTC at $60,000 and an ask of 1.5 BTC at $60,050. If you submit a market buy, you take the $60,050 ask; if you place a limit buy at $60,000, your order joins the bid side and waits.

Reading an order book tells you where liquidity is concentrated and how far a large order might move the price. A common misconception is that the order book shows everything: large traders often hide their intentions using iceberg orders or trade off-exchange, so visible depth is only part of the picture.