Account Model
An accounting design where the network stores a running balance for each account, like rows in a ledger.
Ethereum and many chains that followed it keep an account object holding a balance, a transaction counter called a nonce, and for contract accounts the code and its storage. A transfer simply debits one account and credits another, and a contract call updates whatever the contract's code says, which makes long-lived shared programs straightforward to write. The nonce is required so that a signed transaction cannot be replayed a second time, and it forces a sender's transactions to execute in order. The trade-off is that every account and contract permanently occupies space in state, so the account model grows the data that every node must keep.
Na prática
An Ethereum transaction with a nonce lower than the account's current nonce is rejected outright, which is what prevents an old signed transfer from being replayed.
O equívoco comum
The account model does not make transactions reversible or supervised; an account is a ledger entry keyed by an address, with no operator able to adjust it.