Explain the different isolation levels in ADO.NET transactions.

Short answer: Isolation levels define the level of visibility one transaction has into the changes made by other concurrent transactions. The four isolation levels in ADO.NET are:

Real-world example (ShopNest)

Placing an order updates stock and inserts the order row in one SqlTransaction—either both succeed or both roll back.

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.