Transaction Output

Overview

Bitcoin-style transactions consume previous outputs and create new outputs. One output can pay the recipient, while another returns change to the sender. The sum of outputs cannot exceed the available input value after fees.

Each output has an index within the transaction. A later input references the transaction ID and output index, creating a unique outpoint. The locking script determines the signature, key, hash, or other condition required for spending.

Output design affects privacy and efficiency. Change outputs can reveal wallet behavior, and creating many small outputs can increase future transaction fees. Wallets use coin-selection and change strategies to reduce these costs and avoid unnecessary linkage.

Some outputs are intentionally unspendable, such as data-carrying or burn constructions. Coinbase transaction outputs have maturity restrictions before miners can spend them.

Payment systems should verify the exact output paying the intended address and amount. A transaction can include several outputs, so checking total transaction value is not enough. For tokens or account-based chains, applications usually inspect receipt logs or state changes instead of UTXO outputs.

The term should therefore be interpreted according to the protocol. In UTXO networks, it is a precise spendable object; elsewhere, it may simply describe the result of execution.

Output ownership should not be inferred from address alone when custodians or scripts are involved. One exchange output can represent a deposit for a specific customer only when the correct memo or account mapping exists. Wallets should also label change internally so accounting and privacy tools do not misclassify it as an external payment. Output-level records are essential for accurate UTXO reconciliation and later spending decisions.