What is the difference between Scoped, Singleton, and Transient lifetimes?

Short answer: Transient: A new instance is created every time it is requested. Scoped: A single instance is created per request/HTTP request. Singleton: A single instance is created and shared across the application lifetime. Lifetime Created Per Use Case Transient Every injection Lightweight, stateless services Scoped HTTP Request Web services handling per-request data Singleton App lifetime Logging, configuration, cache

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.