Order Book
A live, ranked list of all outstanding buy and sell orders for an asset on an exchange.
An order book lists every resting bid and ask, stacked by price. Bids sit below the current price, asks above it, and the gap between the best of each is the spread. A trade happens when a buyer and a seller meet in the middle.
The book reveals depth: how much could be bought or sold before the price moves meaningfully. A thick book absorbs large orders quietly; a thin one gaps on the first sizeable trade. Traders read it for hidden walls of supply and demand, though large players sometimes spoof orders to fake them.
Related terms
The highest price a buyer is currently willing to pay for an asset on the order book.
Ask PriceThe lowest price a seller is currently willing to accept for an asset on the order book.
SpreadThe gap between the highest bid and the lowest ask, a basic measure of trading cost and liquidity.
LiquidityHow easily an asset can be bought or sold near its current price without moving that price much.