What is Orphan block

Orphan blocks occur when more than one miner successfully validate a block simultaneously. Since only one block can be added to the chain, the other block is disregarded and termed “orphan block”. The block that generates the longest chain is the one attached to the blockchain. Despite arriving at the solution at the same time, the successful miner with the more elaborate proof-of-work receives the reward, whereas the generator of the orphan block gets no remuneration.

This can happen because there could be a time lag in the network. Nodes could receive the information broadcasted by the different miners at later times and approval doesn’t occur straightaway. This leads to a confusion in the network, which is resolved in this way.