Definition
Block inclusion is the process through which a transaction moves from the mempool into an actual block on a blockchain. It describes the moment when a transaction is selected, ordered, and written into a block’s data structure, transitioning from a pending state to a confirmed on-chain record. Once block inclusion occurs and the block is accepted by the network, the transaction becomes part of the canonical chain history.
This process is closely tied to block building, where a set of transactions is assembled into a candidate block, and to block proposal, where that candidate block is broadcast to the network for validation. Block inclusion therefore represents the decisive step at which a transaction’s status changes from merely broadcast to being durably recorded in a block.
Context and Usage
In most blockchain systems, transactions first enter the mempool and compete for block inclusion based on factors such as priority fee, size, and protocol rules. The entity responsible for block execution applies the selected transactions in a specific order, updating the blockchain’s state and finalizing which transactions are actually included in the block. As a result, block inclusion determines not only whether a transaction is confirmed, but also its relative ordering within a block.
The term is often used when discussing transaction confirmation times, fee markets, and the incentives that influence how a block is constructed. It connects directly to concepts like transaction selection, block structure, and the economic mechanisms that guide which transactions are prioritized for inclusion in the next block.