Order book is a specific Trading coordinate in the Bitcoin knowledge graph. In practical terms, it identifies the subject described here: A ranked list of resting buy and sell orders at each price level. This definition is narrower than promotional usage and should be read together with the implementation, date and evidence attached to the entry.
Order book is best understood as part of a system rather than as an isolated definition. Its related coordinates show the mechanisms, incentives and historical records that give the term practical meaning.
Order book describes how participants value, trade or obtain exposure to bitcoin. Market behavior can affect adoption and mining economics, but it does not rewrite consensus rules. Price evidence and protocol evidence answer different questions.
Understanding Order book helps distinguish a verifiable Bitcoin mechanism or historical record from slogans, products and market narratives.
Primary or authoritative records make these details checkable: an order book records active bids and offers by price and quantity under a venue's matching rules, changing with placement, cancellation, execution and hidden or reserve-order behavior. They should be verified before using the coordinate in analysis.
The practical limit is: it is not a complete map of demand and supply: liquidity is fragmented, spoofable, cancellable and latency-sensitive; snapshots cannot guarantee execution or reveal beneficial ownership. A definition, office, chart pattern or published claim is not by itself a prediction or Bitcoin consensus rule.
For the clearest picture, read this entry together with Bid–ask spread, Market depth, Limit order, Market order, Market microstructure, Bitcoin. The reverse links also lead from Bid–ask spread, Slippage, Market order, Limit order.