Bitcoin Transaction

Overview

A wallet constructs a Bitcoin transaction by selecting UTXOs that provide enough value for the intended payment and fee. It creates one or more recipient outputs and normally a change output back to the wallet.

Each input references a previous transaction ID and output index. The witness or unlocking data proves that the spender satisfies the referenced output’s Bitcoin Script. Nodes verify signatures, scripts, input availability, amounts, weight, and consensus rules. Transaction size is measured through weight and virtual bytes, which affect fees. Adding more inputs usually costs more than adding simple outputs. Fee rate determines competitiveness during congestion, while absolute fee alone can be misleading. A transaction ID identifies the serialized transaction under protocol rules. SegWit also separates witness-related identification considerations. Payment systems should store the transaction ID, block hash, output index, amount, and confirmation status.

Before confirmation, nodes can have different mempool views. Replace-by-fee policies or conflicting spends can change which transaction confirms. After inclusion, later blocks increase confidence, but a reorganization can temporarily remove it. A Bitcoin transaction is not identical to a payment. It can include several recipients, change, data outputs, or consolidation activity. Reliable business processing must inspect the exact output and connect it to an invoice or account rather than using total transaction value.

Transaction replacement and acceleration should be linked to the same business intent. A new hash can represent a fee bump, cancellation attempt, or changed payment. Systems should group related transactions by inputs or replacement policy and should not credit both versions when one finally confirms.

Bitcoin Transaction is closely related to Bitcoin (BTC) and Bitcoin Script, yet those concepts should remain separate in custody and accounting. A relationship to Bitcoin Transaction through a ticker, wrapper, standard, or protocol does not create identical ownership or settlement rights.