What is the ASP.NET Core request pipeline?

The request pipeline is the ordered sequence of middleware components through which each HTTP request and response passes.

A middleware component can inspect or modify the request, perform work before or after the next component, call the next middleware, or short-circuit the pipeline and generate a response itself.

Middleware order matters. For example, authentication must normally run before authorization, and endpoint routing must be configured consistently with the application's endpoint mappings.