Definition
A stale block is a valid block that conforms to consensus rules but is excluded from the canonical blockchain because another competing block at the same height was accepted instead. It arises from temporary chain divergence and is eventually abandoned by the network, leaving its transactions to be confirmed in later blocks or already confirmed in the winning chain.
In Simple Terms
A stale block is a block that was correctly created and briefly accepted by some nodes, but loses out when the network settles on a different block at the same position in the chain. The stale block is then discarded, and the chain continues from the block that the network collectively recognizes as part of the main chain.
Context and Usage
The term stale block is used in discussions of chain selection, fork resolution, and consensus behavior in proof-of-work and similar systems. It is relevant when analyzing network latency, propagation efficiency, and the stability of the canonical chain. Stale blocks are also considered in security analyses, economic modeling of miners’ revenue, and evaluations of effective confirmation depth for transactions.