How web servers talk to applications — a 9-page field guide for developers on what actually happens between an incoming HTTP request and the code that answers it.

It clears up the confusion behind "web server" vs "application server" by treating them as roles rather than products, then explains why Nginx works differently with NodeJS than PHP and why understanding this is important to learn more about how web servers work.

Whiteboard-style diagrams, real config snippets, plain language, and a one-page cheat sheet at the back.