What Is an ‘Orphaned Block’ in Blockchain Technology?

An orphaned block, also known as a stale block, is a valid block that is not included in the main blockchain because another miner found a different valid block at nearly the same time, and the network accepted the other block first. This happens when two miners solve the block puzzle almost simultaneously.

The transactions in the orphaned block are returned to the mempool, and the miner who found it loses the block reward, though they may keep the transaction fees.