> For the complete documentation index, see [llms.txt](https://docs.xpressprotocol.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.xpressprotocol.com/trading/order-book.md).

# Order Book

XPress protocol's order book is fully on-chain and works similarly to centralized exchanges. Orders are matched based on price-time priority.

In contrast to some other on-chain order books, there is no upper bound on the number of orders that can be simultaneously placed on XPress.

All prices allow up to 6 digits of precision, enabling tick sizes of less than 0.001%.