A decentralised order book is a trading mechanism where buy and sell orders on an exchange are matched through a distributed network of nodes, rather than being centralised in a single location or controlled by a single entity. In a decentralised order book, users can submit orders and execute trades without the need for intermediaries or central authorities.

Decentralised order books are typically powered by blockchain technology, which enables secure and trustless peer-to-peer transactions. The order book maintains a record of all buy and sell orders on the network, and the matching process is automated using smart contracts. The order book operates on a decentralised network, which ensures that no single entity has control over the platform.

By contrast, centralised order books are managed by a single entity that controls the platform and the matching of buy and sell orders. The centralised approach relies on intermediaries such as centralised exchanges, brokers, market makers, and custodians to facilitate trades, which can lead to higher fees and reduced transparency.