Transaction processing in the context of blockchain refers to the series of steps necessary to verify, execute, and record a transaction on a blockchain network. This typically involves the creation of a transaction (which may include transferring cryptocurrency or executing a smart contract), broadcasting the transaction to the network, validation by nodes, and inclusion in a block by miners (in proof-of-work systems) or validators (in proof-of-stake systems). Once confirmed, the transaction becomes immutable, meaning it cannot be altered or deleted without consensus from the network participants.