In blockchain technology, transaction confirmation refers to the validation stage of a transaction that takes place after it has been submitted to the network. Once a transaction is initiated by a user, it is broadcasted to the network, where it waits to be picked up by miners (in proof-of-work systems) or validators (in proof-of-stake systems). These nodes verify the transaction against the blockchain's rules, including checking digital signatures and ensuring the sender has sufficient funds. Once confirmed, the transaction is added to a block, making it immutable and irreversible.