Can you explain the ACID properties of a transaction?

Short answer: transaction are invisible to others until the transaction is committed. Durability: Once a transaction is committed, the changes are permanent, even in the case of a system crash.

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.