What does ACID stand for in databases, and why is it important?

• A. Atomicity, Consistency, Isolation, Durability; ensures reliable transactions.
• B. Atomicity, Consistency, Isolation, Durability; ensures reliable and correct transactions.
• C. Accuracy, Coherence, Isolation, Durability; ensures reliable transactions.
• D. Atomicity, Consistency, Integrity, Durability; ensures rollback capability.

Answer: (B)

ACID defines four properties that govern how transactions interact with a database. Atomicity means the whole operation happens completely or not at all; if any part fails, the system reverts everything, leaving no partial updates. Consistency ensures that a transaction moves the database from one valid state to another, preserving all rules and constraints so data remains correct. Isolation makes concurrent transactions appear to run one after another, preventing interference and anomalies from overlapping effects. Durability guarantees that once a transaction is committed, its changes persist even if the system crashes, thanks to logs and recovery mechanisms. Together these properties make transactions reliable and correct in multi-user environments, enabling safe recovery from failures and predictable behavior. The other options use terms that don’t map to the established guarantees, so they don’t capture the precise meanings of atomicity, consistency, isolation, and durability.