What is ACID compliance in a database?

Short answer: ACID stands for: Atomicity: Ensures that all operations in a transaction are completed successfully, or none are.

Explain a bit more

If one part of a transaction fails, the whole transaction fails. Consistency: Guarantees that the database is always in a valid state, adhering to all rules, including constraints, after a transaction. Isolation: Ensures that transactions are executed in isolation from each other, so one transaction does not interfere with another. Durability: Ensures that once a transaction is committed, it is permanent, even in the case of system failures.

Real-world example (ShopNest)

Checkout wraps stock decrement + order insert in a transaction so you never sell stock you do not have.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.