What is the difference between Composition and Inheritance?

Short answer: Inheritance creates an “is-a” relationship, where a subclass inherits behavior and properties from a parent class. It can lead to tight coupling and fragile hierarchies if overused. Composition creates a “has-a” relationship, where a class contains instances of other classes and delegates behavior to them. It’s more flexible and promotes loose coupling.

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.