What is the Strategy pattern and what problem does it solve?

Short answer: The Strategy pattern is a behavioral design pattern that defines a family of algorithms, encapsulates each one, and makes them interchangeable at runtime. It allows the algorithm to vary independently from clients that use it. Problem it solves: Avoids large if-else or switch statements when selecting behavior and promotes flexibility by decoupling the algorithm from the client using it.

Real-world example (ShopNest)

ShopNest payment fees use Strategy: IFeeCalculator with UPI/Card implementations chosen at runtime.

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.