What Is an “Orphan Block” and How Is It Resolved by the Network?

An orphan block, often called a stale block, is a valid block that a miner successfully found but which is not part of the main chain because another miner's block was accepted by the majority of the network first. This happens due to network latency.

When a node receives an orphan block, it is temporarily stored. Once the node receives the parent block that links the orphan block to the main chain, the orphan block is discarded, and the transactions it contained are typically re-included in the next valid block.