Content negotiation (JSON, XML)?

Short answer: ASP.NET Core selects the response format based on the Accept header. JSON is the default. To add XML: services.AddControllers() .AddXmlSerializerFormatters(); Accept: application/xml

Real-world example (ShopNest)

A ShopNest checkout request flows through middleware, hits a minimal API or controller, uses scoped services, and returns ProblemDetails on errors.

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.