Child Block

Overview

Meaning and scope

A child block is a block that directly references another block as its parent and extends that parent’s history by one step. The child contains or derives a parent identifier, executes from the parent’s state, and adds new transactions or consensus data. One parent can have multiple children during a fork.

Mechanism and operation

A child header normally contains the hash or identifier of its direct Block Parent. Nodes use this reference to find the state and consensus context needed to validate the child. The child’s block number, timestamp, resource accounting, and state transition are checked relative to the parent under the active protocol rules. Multiple producers can create valid children for the same parent. This can happen through normal network latency, competing proposals, or an intentional fork. The children begin separate branches, and each later child extends one of those branches. Best Chain selection evaluates the accumulated work, votes, checkpoints, or other protocol weight to decide which path becomes the best and canonical chain.

Practical payment example

A new block references an earlier parent. The payment monitor counts only descendants of the accepted canonical branch when calculating confirmation depth.

Operational checks

Confirmation depth is often counted by the number of canonical descendants above a block. A child adds one level of depth, but it may be replaced if another branch wins. Payment systems can use child links to validate ancestry and detect reorganizations. If a new canonical child references a different parent than expected, the local chain view may have changed or data may be missing.

Distinctions and limits

A grandchild or later block descends from an earlier block but is not its direct child. Stronger finality depends on the network’s consensus mechanism, not the family-tree label alone.

Related reading

Related definitions: Block Parent, Best Chain.