Single Instance:?

Short answer: The Singleton class (ConfigurationManager) only allows one instance to be created. The instance is stored in the static _instance field, ensuring that only one object exists.

Real-world example (ShopNest)

Use a GoF pattern in ShopNest only when it removes duplication or makes a change safer—explain the problem it solves in the interview.

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.