An order book, also called a quote book or a list of bids and offers, is a structured listing of all current limit orders to buy and sell a cryptocurrency or other exchange instrument. All orders submitted by traders are gathered into a single table and sorted by price, forming a clear picture of current supply and demand.

The order book is traditionally divided into two parts: buy orders (bids) are placed below the current price, while sell orders (asks) are above it. The difference between the best buy price and the best sell price is called the spread. The narrower the spread and the larger the volume of orders near the market price, the higher the instrument's liquidity and the easier it is to execute trades without significant slippage.

Analyzing the order book helps traders assess market sentiment and potential support and resistance levels. Large clusters of orders may indicate buyer or seller interest, but it is worth bearing in mind that some orders may be placed and removed in order to influence the perception of the market, so it is sensible to interpret order book data together with other analysis tools.