Exchange order book: what it is and what it shows
An exchange order book lists open buy and sell orders by price. It shows the spread and depth, while trade history shows completed trades only.
Vahe HakobyanEditor-in-chief
Updated Oct 6, 20263 min readFact-checked
On this page
- Bids are buy orders, asks are sell orders, sorted best price first.
- The spread is the gap between the best bid and best ask.
- Depth shows available size at each price; thin depth worsens fills.
- Limit orders rest on the book; market orders fill against open orders.
- Trade history shows completed trades, while the book shows open orders.
Centralized crypto exchanges use order books to connect buyers and sellers. The book changes in real time as people place, change, or cancel orders.
What does an order book show?
The order book shows the open orders on one exchange for a single trading pair. Buy orders are bids, and sell orders are asks. The exchange sorts bids from highest price to lowest and asks from lowest price to highest.
How do traders read depth and spread?
The spread is the gap between the best bid and the best ask. A small spread usually means the market is liquid. Depth shows how much crypto is available at each price. Thin depth means your order may fill at worse prices, and large trades can move the market through several price levels.
How do orders fill and rest?
A limit order sets a price you are willing to accept. A market order takes the best available price right away. The exchange matches orders through its matching engine.
- Limit orders rest on the book. They wait at your price until another trader fills or you cancel.
- Market orders fill against existing orders. They take the best bids or asks available.
- Partial fills can happen. A large market order may fill in pieces across several resting orders.
How is it different from trade history?
An order book shows open orders that have not traded yet. Trade history shows completed trades that already happened.
Frequently asked questions
A matching engine is software that pairs buy and sell orders. It ranks orders by price and time, then executes trades when prices align.
Each exchange has its own users, market makers, and trading pairs. Liquidity is not shared, so the same pair can have different spreads and depth.
Yes, most exchanges show the live order book on public pages. You can watch bids, asks, spread, and depth without an account.
