How price really moves: the order book
Every price change happens in the order book: trades use up the orders waiting at the best price, or traders pull and move their orders. News matters because it changes what people do there.
- What bids, asks and the spread are
- Why a market order moves price and a waiting limit order does not
- How a thin book turns a normal order into slippage
Before you start: No trading experience needed. Every new word is underlined the first time — hover or tap it for a short definition.
Two queues of waiting orders
Every exchange keeps an order book for each trading pair: a live list of orders that are waiting to be filled. Orders to buy — bids — sit below the current price. Orders to sell — asks — sit above it.
The highest bid and the lowest ask are the best prices on offer right now. The gap between them is the spread. On BTC/USDT it is usually one cent — the smallest price step the exchange allows, its tick size. On small coins the spread is often far wider.
Limit orders wait, market orders take
A limit order says: "buy (or sell) at this price or better". If no one is willing to trade at that price yet, the order joins the queue and waits. Waiting orders are the book's liquidity.
A market order says: "trade now, at whatever the book offers". It never waits. It takes the best price available and removes those orders from the book.
A market order eats the book
If the best level is too small for a market order, the order takes all of it and moves on to the next level, and the next. When the cheapest asks are used up, trades happen at higher prices and the best ask moves up. That is what a rising price looks like from inside the book.
Price can change without a trade
Orders in the book are not promises. Traders cancel and move them all the time. If the sellers at the best ask cancel, the next ask up becomes the best one: the price shown by the book has risen although nobody traded.
Charts show something different: the price of the last trade. Both views matter, and later lessons use both.
Thin books, big moves
The same order moves a thin book far more than a deep one. The extra cost — the gap between the price you expected and the average price you got — is slippage. In the explainer above, $1.5M of BTC moves the best ask by about 0.02%, while $30,000 of DODO moves it by about 1.6% — fifty times less money, a move about eighty times bigger. How much waits near the price is the book's depth.
That is why the same news can move a small coin much more than BTC: fewer orders stand in the way.
BTC/USDT order book, 27 October 2026, 11:34 UTC: the spread was $0.01; 79.1 BTC of bids and 105.2 BTC of asks waited within 0.1% of the price. It would have taken a market buy of about 105 BTC (≈ $8.4M) to lift the best ask by 0.1%.
- The book is two queues: bids below the price, asks above it; the gap is the spread.
- Waiting limit orders add liquidity; market orders take it.
- Price moves when market orders use up the best levels — or when waiting orders are pulled.
- The thinner the book, the further the same order moves price.
Open BTC in the terminal and watch its order book
Education only, not financial advice · Updated 27 Oct 2026 · Data: Binance · Report a mistake