Transaction Input

Transaction input is an element of a transaction in a UTXO-based blockchain that identifies previously created funds being spent by the new transaction.

An input normally references a specific output of an earlier transaction and includes the data required to prove that the funds can be spent. In Bitcoin-like systems, this can include a digital signature and other unlocking data.

Inputs and outputs

A transaction can contain multiple inputs. Their combined value provides the funds used to create new outputs and cover the transaction fee.

This structure makes it possible to trace individual UTXOs through the chain. Account-based blockchains use a different accounting model and therefore do not use transaction inputs in the same way.