Order Book
The live list of buy and sell orders for an asset, ordered by price — the primary display in every trading interface.
Industry & DomainAn order book lists outstanding buy orders (bids) and sell orders (asks) by price, with the quantity available at each level. The gap between the highest bid and lowest ask is the spread, and the accumulated quantity at each level is the depth — which together tell a trader what a given order size will actually cost, as opposed to what the last trade printed at.
As an interface it is one of the densest components in consumer software: numbers changing several times a second, colour carrying direction, and precision decisions that change what traders can see. The mistakes are consistent — animating every update so nothing can be read, using red and green as the only direction signal, and proportional figures that make columns impossible to scan. Price columns need tabular figures, updates need throttling to a readable rate, and direction needs a signal besides colour.
In practice
An exchange animated every order book row on change. At active moments the display was unreadable and traders reported “lag” that was not present in the data. Throttling updates to five per second with a brief highlight instead of a transition removed the complaint entirely and reduced CPU use on the page by about half.
Where teams get it wrong
- Animating every update, which makes the numbers unreadable exactly when they matter.
- Red and green as the only direction indicator.
- Proportional figures in price columns, so magnitudes cannot be scanned.
- Showing price levels without cumulative depth, which is what determines execution cost.
- Precision that changes between rows, making comparison harder than it needs to be.
Learn more
You may ask
Frequently Asked Questions
What does an order book show?
Outstanding buy and sell orders by price level with the quantity at each, plus the spread between the best bid and best ask. Cumulative depth shows what a given order size would actually cost to fill.
What is market depth?
The cumulative quantity available at each price level. Deep books absorb large orders with little price movement; thin ones mean a moderate order moves the price against the trader.
Related terms
All terms- Data TableA grid of rows and columns for scanning, comparing and acting on records — the screen most B2B users spend their day inside.
- TokenomicsThe economic design of a token — how it is created, distributed, used and removed, and whether those rules hold under real incentives.
- Status IndicatorA persistent signal of a system or record's current condition — distinct from a message about something that just happened.
- Fiat On-RampThe path from conventional money into crypto — the step where most first-time Web3 users stop.
Defined by Mara Last reviewed .
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