What is Order book?
The live list of buy and sell orders at each price on an exchange. Its depth is the honest picture of a market's liquidity — and where makers and takers meet.
The order book is the market's ledger of intent: every resting buy order (bids) and sell order (asks) at every price, stacked in two columns. The gap between the best bid and best ask is the spread; the volume stacked near the price is depth — the honest, hard-to-fake picture of a market's liquidity.
Reading one repays the minute it takes: thin books mean your market order will slip, walls of orders show where other traders have drawn lines, and a book that's mostly empty is a coin telling you how hard leaving will be. It's also the venue where maker/taker economics happen — your limit orders join the book; your market orders eat it.
See it in practice
Related terms: Maker/taker fees · Liquidity · Spread · full glossary
FAQ
Why does the order book matter if I just use instant buy?
Because the instant-buy price is derived from the book plus a margin. Platforms with order-book interfaces almost always price the same trade better — the book is where the real market lives.
What are "buy walls" and "sell walls"?
Unusually large orders stacked at one price — sometimes genuine accumulation limits, sometimes theatre placed to influence sentiment and pulled before filling. Depth that vanishes when approached was never really there.
General information only, not financial advice. Definitions are maintained in our fact database and reviewed with the daily rebuild.