Accounts & State

Ethereum has two account types: Externally Owned Accounts (EOAs), controlled by private keys and used by humans, and Contract Accounts, controlled by their code. Unlike Bitcoin's UTXO model, Ethereum uses an account-based model where each account has a balance, nonce (transaction count), code (empty for EOAs), and storage. The global state is a mapping of all accounts, stored in a Merkle Patricia Trie. Every transaction modifies this state, and the state root hash is included in each block header.