In trading, 'book' is short for order book — the electronic list of all pending buy and sell orders for a particular asset, organized by price level. The order book displays market depth by showing the quantity of orders at each bid and ask price, helping traders gauge supply and demand dynamics. A deep book with many orders indicates high liquidity, while a thin book may lead to slippage on larger orders. Traders analyze the book to identify support and resistance levels and detect potential whale activity.
Example
“The order book showed a massive cluster of buy orders at the $25,000 level, suggesting strong support for Bitcoin at that price.”