Order Book
A real-time list of outstanding buy and sell orders for an asset on an exchange, used by CEXs and some hybrid DEXs.
Order Book — An order book is a real-time ledger of all outstanding buy and sell orders for a trading pair on an exchange, organized by price level. On centralized exchanges, order books are the primary mechanism for price discovery and trade matching, showing the depth of liquidity available at each price point.
What Is an Order Book?
An order book is a continuously updated list of buy orders (bids) and sell orders (asks) for a specific trading pair. The highest bid and lowest ask define the current market price and spread. Traders can place limit orders at specific prices, which sit in the order book until matched by a counterparty, or market orders that execute immediately against the best available price.
On centralized exchanges like Binance, Coinbase, and Bybit, order books are the standard trading mechanism. They provide transparent visibility into market depth and allow traders to see exactly how much liquidity exists at each price level.
How Order Books Work
The order book organizes all open orders by price. Buy orders are sorted from highest to lowest (the best bid is at the top). Sell orders are sorted from lowest to highest (the best ask is at the top). When a new order's price matches or crosses an existing order, a trade executes.
For example, if the order book shows a best bid at $1.00 and a best ask at $1.02, a market buy order would execute at $1.02. A limit buy order placed at $1.01 would sit in the book until a seller agrees to that price. The gap between best bid and best ask is the spread, which represents the cost of immediate execution.
Market makers maintain order books by placing both bid and ask orders at multiple price levels. Without market makers, order books become thin, spreads widen, and trading becomes impractical for all participants.
Why Order Books Matter
Order books provide the price discovery mechanism for centralized exchanges, which still handle the majority of crypto trading volume. For token projects listed on CEXs, maintaining a healthy order book with tight spreads and deep liquidity is essential for attracting traders and maintaining exchange listing status.
OpenLiquid's CEX market maker automates the process of maintaining order book depth by placing and managing bid and ask orders across multiple price levels, ensuring consistent spread and depth metrics.
Related Terms
Bid-Ask Spread
The difference between the highest price a buyer will pay (bid) and the lowest price a seller will accept (ask); a market maker's primary revenue source.
Read definition Volume Bot & Market MakingMarket Maker
An entity (human, firm, or bot) that provides continuous two-sided quotes on an exchange to ensure trade execution for others.
Read definitionFrequently Asked Questions
Common questions about Order Book in cryptocurrency and DeFi.
An order book matches individual buy and sell orders placed by traders. An AMM uses a mathematical formula and pooled liquidity to execute trades. Order books are used on centralized exchanges, while AMMs power most decentralized exchanges. Order books typically offer tighter spreads but require active market makers.
Most DEX tokens trade through AMM pools, which do not have traditional order books. However, some DEX protocols like dYdX and Serum use on-chain order books. For AMM-based tokens, the equivalent information is pool depth and the AMM's pricing curve.
A healthy order book has tight spreads (under 0.5%), symmetrical depth on both sides (similar total value in bids and asks), multiple price levels with orders, and consistent liquidity that does not disappear during volatility. Thin or one-sided order books indicate poor market making.
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