Transactions are the things that give a blockchain purpose. They are the smallest building blocks of a blockchain system. Transactions generally consist of:
- a recipient address,
- a sender address,
and a value.
This is not too different from a standard transaction that you would find on a credit card statement.
A transaction changes the state of the agreed-correct blockchain. A blockchain is a shared, decentralized, distributed state machine. This means that all nodes (users of the blockchain system) independently hold their own copy of the blockchain, and the current known "state" is calculated by processing each transaction in order as it appears in the blockchain.
