The Order Book and Bid-Ask Explained (PDF)

The chart says 100.05, you press buy, and the order fills at 100.08. Or you sell straight after buying and you are already down, though price has not moved. Nothing went wrong. You met the order book: the list of every buyer and seller waiting, and the gap between them.

This guide shows you how to read an order book from zero: the bids, the asks, the spread between them, and the depth behind them, and what each of those costs you when you trade. It is 39 pages, written for someone who has never traded, with every word explained before it is used.

Every idea is drawn with the words on the picture: one row of an order book read left to right, the spread worked out as a percentage, a market order walking up the book row by row, two example books with the same spread but very different depth, a big order that vanishes before it trades, and a real Dogecoin wick. Then example spreads are set against stops measured on real XRP and Dogecoin trades, you work two out yourself, and it ends with a five-check routine to run before any market order.

WHAT'S INSIDE

- Every part of the order book: Bids, asks, the spread, the mid price and the depth, each labelled on a picture of a book.

- What the spread really costs: Worked out as a share of a normal stop measured on ten coins: 1.12% on 1-hour candles at a 0.01% spread, 27.96% at 0.25%.

- Why big orders fill at worse prices: A market order walking through a thin book and a thick book, with the average price worked out for each.

- Maker or taker: When to join the bid with a limit order and when to cross the spread, and what each choice gives up.

- Reading the book honestly: Why a large waiting order is not a promise, and what a candle cannot show you about the book.

WHAT YOU'LL BE ABLE TO DO

- Read the best bid, best ask and spread on any order book.

- Work out the spread as a percentage and as a share of your stop.

- Estimate the average price of a market order from the book.

- Choose between joining the bid and crossing the spread on purpose.

AN HONEST NOTE

No guide can tell you what price will do next, and this one does not try. The stops are measured on real prices; every spread and order book is a labelled example, because free price data does not record the book. No win rates, no profit figures, no promises. Educational, not financial advice.

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