> For the complete documentation index, see [llms.txt](https://docs.strixlab.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.strixlab.io/trading/order-book.md).
# The Order Book
The order book is the live list of every open buy and sell order for a market. Strix Lab runs a **central-limit order book (CLOB)** — the same model used by professional exchanges — so you always trade against real orders from real users, never against the platform.
### The four terms you need
Term
Meaning
Bid
The highest price a buyer is currently willing to pay.
Ask
The lowest price a seller is currently willing to accept.
Spread
The gap between the best bid and best ask.
Depth
How many shares are available at each price level.
Together, depth and spread tell you how **liquid** a market is — how easily you can trade without moving the price. A tight spread with deep levels means lots of active participation: you can trade larger amounts at prices close to the current market. A wide spread with thin depth means fewer participants, so large orders will move the price more.
### Reading the book: an example
Here's a simplified book for a Yes share:
| Sell orders (asks) | Price | Buy orders (bids) |
| ------------------ | ------------------ | ----------------- |
| 400 shares | 69¢ | |
| 250 shares | 68¢ | |
| 120 shares | **67¢** ← best ask | |
| | **65¢** ← best bid | 200 shares |
| | 64¢ | 350 shares |
| | 63¢ | 500 shares |
What this book tells you:
* The **spread is 2¢** (67¢ ask − 65¢ bid).
* If you place a **market buy**, you pay **67¢** — the best available ask. Buy more than 120 shares and the remainder fills at 68¢, then 69¢, walking up the book. That's depth in action.
* If you place a **limit buy at 66¢**, nothing matches yet — your order sits in the book between the current best bid and ask, becoming the new best bid, and waits for a seller to meet it.
### How a trade matches
When your order **crosses the spread** — a buy at or above the best ask, or a sell at or below the best bid — it matches immediately against the waiting orders. Anything that doesn't match right away **rests in the book** at your price until another trader meets it.
* The order that crosses the spread and matches instantly is the **taker**.
* The waiting order that gets matched is the **maker** — it "made" the market by offering a price in advance.
This is the same distinction from [Fees](https://docs.strixlab.io/trading/fees): **orders that wait in the book trade free (maker); orders that match instantly pay a small fee (taker).**
**Why use a limit order at all?** Two reasons: you set your own price instead of accepting the market's, and if it fills, you've paid zero fees. The tradeoff is certainty — a limit order may fill in seconds, hours, or never. Market orders buy certainty; limit orders buy price. As you trade more, you'll use both.
### Yes and No are two views of one book
Because Yes + No ≈ $1, a bid to buy No at 30¢ is economically identical to an ask to sell Yes at 70¢ — the [mirror-image principle](https://docs.strixlab.io/trading/how-markets-work#outcome-shares) from How Markets Work. The Strix order book reflects both sides, so the liquidity you see is the combined interest of everyone in the market, whichever side they chose.
### Your own orders
Your resting limit orders are highlighted at their price level in the book. Click the badge on a level to cancel your order there. The [price ladder](https://docs.strixlab.io/trading/price-ladder) is the fastest way to work the book — place and cancel orders directly on it with a single click.
{% hint style="info" %}
The book, the price chart, and your own open orders all update live in real time (over a WebSocket connection) — no refreshing needed.
{% endhint %}
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