What is Order Book?
A real-time list of all pending buy and sell orders on an exchange, organised by price level — the visible supply and demand for an asset.
The order book is a live record of every limit order that has been placed but not yet filled, sorted by price. It shows exactly who wants to buy and at what price, and who wants to sell and at what price.
Structure:
| Side | Name | Meaning |
|---|---|---|
| Buy orders | Bid | Highest price buyers will pay |
| Sell orders | Ask | Lowest price sellers will accept |
The gap between the highest bid and lowest ask is the bid-ask spread.
Reading the order book:
A typical BTC/USDT order book might show:
If you place a market buy, you immediately fill at $50,010 (the ask). If you place a limit buy at $49,990, your order joins the bid side and waits.
What the order book reveals:
Order book manipulation:
Experienced traders know that large visible orders ("walls") are sometimes spoofed — placed to manipulate sentiment and then cancelled before execution. Don't trade purely on order book walls without confirming with other signals.