Intermediate · Market structure
How crypto order books, spreads and market makers work
- Key takeaway 1
A market order fills right away at the best available price; a limit order fills only at your price or better.
Source: Investor.gov: Types of orders
- Key takeaway 2
The bid-ask spread is the gap between the highest buy offer and the lowest sell offer.
Source: Investor.gov: Bid-ask spread
The short lesson
An order book is a live list of offers to buy (bids) and sell (asks).
- Market order: fast, but the price can slip in a thin book.
- Limit order: you set the price; it may never fill.
- Market makers post both bids and asks and earn from the spread. They keep the book full.
Why it matters to you
- A wide spread is a hidden cost on top of fees.
- Small coins often have thin books, so prices jump.
- The “last price” on a chart may differ from what you can actually trade at.
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Common questions
Is a DEX the same?
Some DEXs use order books; many use AMM pools instead.
Why did my order fill at a different price?
A market order takes what is available, which can move in fast markets.
Sources
Sources checked October 31, 2026. Rules change; check the official source before acting.
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