UTXOs: The Digital Coins Behind Bitcoin's Uniqueness
Bitcoin's UTXO model is a unique aspect of its design. Unlike traditional bank accounts, where balances are stored as one number, Bitcoin's balance is made up of multiple unspent transaction outputs (UTXOs). A UTXO represents a piece of Bitcoin that has been received but not yet spent.
When someone sends you Bitcoin, the transaction creates an output that belongs to you. Until you spend that output, it is considered a UTXO. Once you spend it, that UTXO is no longer available and becomes spent.
The UTXO model helps Bitcoin verify transactions without relying on a traditional centralized account balance. When you try to spend Bitcoin, the network checks whether the UTXOs you're using are actually unspent. If someone tries to spend the same UTXO twice, Bitcoin nodes can reject the transaction, preventing double spending.
UTXOs can be combined when making transactions, and new outputs are created for any change. The number of UTXOs used as inputs can affect the size of a Bitcoin transaction, which in turn affects fees. Dust UTXOs are extremely small outputs that may not be economical to spend due to high transaction fees.