How Does Bitcoin’s UTXO Model Prevent Double-Spending?
The Unspent Transaction Output (UTXO) model ensures that every transaction must consume an existing, unspent output from a previous transaction. Once a UTXO is spent, it is removed from the set of available UTXOs.
This means the same output cannot be used as an input for two different transactions. Miners validate that the inputs for a new transaction are indeed unspent and have not been recorded elsewhere on the blockchain.
This fundamental mechanism, combined with the blockchain's consensus, makes double-spending computationally infeasible.
Glossar
Unspent Transaction Output
Concept ⎊ Unspent Transaction Output is the foundational accounting concept in Bitcoin, where a transaction's value is not stored in an account balance but rather as an available, spendable output from a prior transaction that has not yet been used.
UTXO
Model ⎊ UTXO, or Unspent Transaction Output, represents the accounting model used by Bitcoin and other similar blockchains.
Utxo Model
Architecture ⎊ The Unspent Transaction Output (UTXO) model represents a distinct approach to tracking cryptocurrency ownership, differing fundamentally from account-based systems.