Can you explain the principles of transactional integrity in databases, known as ACID?

ACID is a set of principles that ensure reliable and consistent transactions in databases:

• Atomicity: The transaction is completed entirely or not at all. If any operation fails, all changes are rolled back.
• Consistency: After the transaction, the database remains in a valid state, satisfying all rules and constraints.
• Isolation: Parallel transactions do not affect each other, as if they were executed sequentially.
• Durability: Once a transaction is committed, its changes are permanent, even in case of system failures.

Example: transferring money between bank accounts involves a transaction that debits one account and credits another. If one operation fails, both should be rolled back to prevent data inconsistency.