Atomicity - Each transaction is "all or nothing": if one part of the transaction fails, the entire transaction fails, and the database state is left unchanged.
Consistency - Any transaction will bring the database from one valid state to another.
Isolation - Concurrent execution of transactions results in a system state that could have been obtained if transactions are executed serially.
Durability - Once a transaction has been committed, it will remain so, even in the event of power loss, crashes, or errors.