Foundations of Blockchain

Transaction input and output

Transactions are primarily constructed with input and output. Each transaction can have multiple inputs and outputs. Unlike account-based bookkeeping, Bitcoin needs to keep track of the output of every transaction. A node needs to have all the transaction output information in order to know the spendable balance of an account. The output can later be referenced in a transaction's input whenever a user wants to spend their cryptocurrency. This output consists of indivisible chunks of currency and can only be broken down after they are consumed in a transaction. The output that is not referenced in any of the transaction's input is referred to as unspent transaction output or UTXO.

Whenever a user wants to spend ...