What are DataSet and DataTable in ADO.NET?

Short answer: DataSet: A collection of DataTables and relationships that represent the data in a disconnected mode.

Explain a bit more

A DataSet can hold multiple DataTables, each corresponding to a database table or view. It's also capable of handling data relationships, such as parent-child relationships. Example: A DataSet might hold a DataTable for customers and another for their orders. DataTable: A single table of in-memory data, which is part of a DataSet. It represents one database table and allows you to work with the data offline. Example: A DataTable for the Customers table that contains rows representing each customer.

Real-world example (ShopNest)

For large order exports, ShopNest uses SqlDataReader (forward-only, fast). DataSet is heavier and mainly for disconnected editing scenarios.

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.