The following diagram illustrates the UTXO model. In this traditional model, popularized by Bitcoin:
An address has some unspent balance.
A transaction can be created to transfer some or all the unspent balances from one more unspent addresses to one or more other addresses. In the illustration below, the first transaction transfers amounts 10, 15, and 5 to 3 other addresses. The remaining unspent balance (of 70) is transferred to a new address, unless the sender specifies an address to return the unspent balance to. Note that the original address would have zero balance once this transaction is finalized, unless that address is used to return the unspent balance.
All addresses that received the amounts are eligible for creating transactions to transfer funds to other addresses. In the following example, transactions 2 and 3 continued to transfer funds to other addresses, leaving a final balance of 40. But notice that after a transaction is finalized, the original addresses have zero balances unless they are used to return unspent balances.