What is a 422 Unprocessable Entity?

Short answer: It indicates the request was well-formed (valid syntax) but could not be processed due to semantic errors. 👉 Example: Submitting a form where email is valid format but already exists.

Real-world example (ShopNest)

ShopNest exposes REST APIs for cart and checkout. Controllers stay thin; business rules live in application services.

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.