Account model

In an account-based blockchain, the state is a table of accounts, each with a balance, a nonce and, for contracts, code and storage. A transfer simply subtracts from one balance and adds to another, much like a bank ledger. Ethereum distinguishes externally owned accounts, controlled by private keys, from contract accounts controlled by code.

The model makes smart contracts much easier to write, because a contract can read and update its own storage and the balances it holds directly. It also keeps transactions small and simple for users. Ethereum, BNB Smart Chain, Solana, Tron and most other programmable networks use some form of account model.

Each account carries a nonce that must increase with every transaction, which prevents replays but also means a stuck transaction blocks all later ones from that account. Reusing one address for everything is the norm, which hurts privacy compared with UTXO wallets that generate fresh addresses. Parallel execution is also harder when many transactions touch the same accounts.