What Is an ‘Orphan Block’ and How Is It Handled by the Network?

An orphan block (also called a stale block) is a valid block that is successfully mined but is not included in the main chain because another block was found and propagated across the network faster. It is a temporary fork.

When a node receives an orphan block, it is usually discarded, and the miner who found it loses the block reward, though their transactions are eventually re-mined into the main chain.