Transaction

A bitcoin transaction is a signed data structure that consumes existing unspent transaction outputs (UTXOs) as inputs and creates new outputs locked to recipients' addresses. Once buried in the blockchain it is effectively irreversible. The network confirms a new block of transactions roughly every ten minutes and processes on the order of 300,000 to 500,000 transactions per day.

How it works

Each input must be spent whole, so payments typically create two outputs, one to the recipient and one returning change to the sender. The difference between total inputs and total outputs is the fee, claimed by the miner who includes the transaction. Digital signatures prove the spender controls the keys behind each input, and every node independently verifies every signature and rule before relaying. Unconfirmed transactions wait in the mempool, where miners select by fee rate, which is why fees rise when demand for block space spikes. After about six confirmations, roughly an hour, reversal is considered economically infeasible because it would require redoing the accumulated proof of work.

In the gold vs bitcoin debate

A confirmed bitcoin transaction is final settlement of the bearer asset itself, comparable to physically handing over gold, not to a card payment, which is a revocable message atop layers of credit. Gold achieves that finality only in person; at distance it settles through custodial ledger entries like London's unallocated accounts, reintroducing counterparties. Bitcoin's claim is settlement with gold's finality at the speed and reach of the internet, and the transaction is the unit in which that claim is delivered.