Order Book
Also known as: Trade Ledger, Market Depth Book, Order Matching System
A list of buy and sell orders organized by price level, used by exchanges to facilitate trading.
An order book is a real-time, digital list of buy and sell orders for a specific asset, organized by price levels. It's used by centralized and some decentralized exchanges (DEXs) to match buyers and sellers. Buy orders (bids) and sell orders (asks) are continuously updated as traders place or cancel orders. The highest bid and lowest ask define the market spread. Order books are essential for market transparency, liquidity analysis, and price discovery. While common in traditional finance and centralized crypto exchanges, some DEXs like dYdX and Serum also implement on-chain or hybrid order books.