The complete collection of all unspent transaction outputs currently available on a blockchain network at any given point in time. The UTXO set represents the current state of ownership for all coins on the network and must be maintained and validated by every full node. As the network processes more transactions, the UTXO set grows and shrinks dynamically, and its size is an important metric for blockchain scalability and node resource requirements.
Example
“Bitcoin's UTXO set contained over 140 million entries, requiring full nodes to maintain several gigabytes of indexed data to validate new transactions.”