If you have ever opened the raw node:http module and tried to write a real server with it, you remember the moment. You wrote http.createServer((req, res) => { ... }) . Then you tried to read JSON from the body and discovered there is no req.body . You parsed it with streams. Then you tried to route a POST /users differently from GET /users and ended up with a giant if/else ladder. Then you added auth, logging, error handling, CORS, and the file became unreadable. Node gave you a great low level engine, but a real web server needs a friendly chassis on top. Express is that chassis. That is the gap Express fills. What is Express, really Think of Express as a small assembly line for HTTP requests . A request walks in one end. It passes through a series of stations, where each station does one thing: parse the body, check the cookie, log the URL, look up the user, validate the input. At the end, a route handler builds a response. The response walks back out the door. Each station is a middleware .…