VOUT

A VOUT is a transaction outpoint. Each VOUT contains a piece of script which can be used to contain a piece of data, hold a token or lock a quantity of Satoshis. The Bitcoin Protocol allows each transaction to include up to 2⁶⁴ outpoints however the actual number allowed will be configured by miners.

Unspent Transaction Outputs

If a VOUT has not been spent, it is referred to as an Unspent Transaction Output and can be used in the creation of a new transaction. Once a VOUT has been used as an input to a transaction that has been sent to the mining network it is considered spent and can no longer be used in a new transaction.

Zero value outptuts

VOUTS that do not contain a value in Satoshis are often used to hold scripts that carry large data items or tokens. Predominantly these are used in False Return outputs as a means to attach data to bitcoin transactions. These outputs are still valid UTXOs and can be used as inputs in a transaction, with locking conditions being applied as normal. The dust rules implemented early on in Bitcoin's history preclude the creation of complicated scripts using zero value outputs until miners remove the limits on minimum values for outputs using complex scripts.