What is the IDisposable interface?

Short answer: Provides Dispose() method for releasing unmanaged resources. class FileHandler : IDisposable

Example code

{
public void Dispose() => Console.WriteLine("Resources released"); }

Real-world example (ShopNest)

Checkout calls IPaymentGateway.Charge(). Razorpay and Stripe adapters implement the same interface, so ShopNest can switch gateways without rewriting the order service.

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.