Mastering Blockchain Programming with Solidity

Ethereum transaction

A transaction on an Ethereum blockchain is required to transfer ETH from EOA or for smart contracts to change state, perform an action, or read a state of a contract. A transaction can only be initiated from an EOA and it can further initiate other internal transactions.

For example, an EOA wallet initiates a transaction to call a function of contract A, and this contract calls another function of contract B. In this case, a transaction is initiated from an EOA to contract A and then an internal transaction is initiated from contract A to contract B.