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.