What is ACID in databases? Tell about each property.

ACID is a set of properties of transactions in databases that guarantee correctness and reliability of operations:

• Atomicity — a transaction is completed in full or not at all. If something goes wrong, all changes are rolled back.
• Consistency — after a transaction completes, the database remains in a correct state, satisfying all rules and constraints.
• Isolation — parallel transactions do not affect each other, as if they were executed sequentially.
• Durability — after a transaction is committed, its changes are saved in the database even in case of failures (e.g., power outages).

These properties ensure data integrity and predictable system behavior when working with transactions.