Why should interfaces be specific and small?

Short answer: Small, specific interfaces: Promote separation of concerns Make classes easier to implement and test Reduce the risk of breaking changes Avoid forcing classes to implement irrelevant methods Increase reusability and readability In contrast, large interfaces force classes to implement methods they may not need — leading to fragile and cluttered code.

Real-world example (ShopNest)

Patterns in ShopNest should solve a real pain (swappable payments, test seams)—not be added for decoration.

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.