Understanding the Order Book
Trading Mastery
10 min read
Explore the limit order book structure, how resting orders create liquidity, and what the depth of market reveals about supply and demand.
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10 min read
Explore the limit order book structure, how resting orders create liquidity, and what the depth of market reveals about supply and demand.
If you want to see what’s really going on in the market—not what people say, but what they’re doing—you need to understand the order book.
The order book is like an X-ray of the market’s intent. It shows you where people want to buy and sell, at what prices, and in what sizes. For traders, it’s one of the most powerful tools available—but it’s often misunderstood or ignored.
But before you can read the order book correctly, you need to understand the types of orders that traders place. That’s what actually fills the order book—and what causes prices to move.
All trading orders fall into two basic categories: market orders and limit orders.
Example: You place a market buy order for 1 BTC. It instantly buys from the lowest available ask—say, at $64,000.
Example: You place a limit buy order for 1 BTC at $63,500. Your order sits in the book, waiting for someone to sell to you at that price.
| Type | Execution | Role | Risk |
|---|---|---|---|
| Market Order | Immediate | Takes liquidity | Worse-than-expected fill |
| Limit Order | Delayed | Provides liquidity | Might never be filled |
Now that you know the two core order types, the order book will make much more sense.
The order book is a real-time list of all limit orders currently waiting to be filled on an exchange. It doesn’t show market orders—those get executed and disappear.
It contains:
Each level includes:
Here’s a simple order book snapshot:
| Price (USD) | Amount (BTC) | Type |
|---|---|---|
| 64,100 | 2.5 | Ask |
| 64,000 | 3.0 | Ask |
| 63,900 | 1.2 | Ask |
| 63,800 | ——— Mid ——— | |
| 63,700 | 1.5 | Bid |
| 63,600 | 2.8 | Bid |
| 63,500 | 3.5 | Bid |
Trades happen when a market order hits a limit order:
Each time this happens, the trade moves price slightly in that direction.
Price doesn’t move because of predictions. It moves when someone chooses to buy or sell at a different price than the last trade.
The order book helps traders:
Example: If there’s a huge wall of buy orders at $63,000, that might act as a support level… unless those bids disappear before price reaches them.
Knowing what kind of orders move the market helps you:
But be cautious:
Drag the imbalance slider to see how bid/ask volume shifts create directional pressure. Notice how the ratio changes as one side of the book grows thicker.