How NestJS Handles the Journey from HTTP Request to Response

Every interaction with a web app — such as clicking a login button — triggers a structured internal process before a response is returned to the user. In NestJS, an incoming request is first received and routed to the appropriate handler, then checked for authorization before any real processing begins. The framework organizes this flow into distinct steps, each with a single responsibility, to keep the system reliable and secure. Backend engineer Peace Melodi explains this lifecycle using an everyday analogy of a letter moving through a mail system. The core takeaway is that actions appearing instant on screen are backed by deliberate, layered processes designed for order and safety.