How to build a login system where the server doesn't need to remember anything about you. Here's the problem with building any application that has user accounts: how does the server know that the person making a request is actually who they say they are? You log in once. But then you visit 10 different pages, make 15 API calls, upload a file. Each of those is a separate HTTP request, and HTTP is stateless — every request is completely independent. The server has no memory of the previous one. So how does it know you're still logged in? The answer is authentication tokens — and the most popular one is JWT (JSON Web Token). You log in, the server gives you a token, and you show that token with every request. No session storage. No database lookup. The token itself proves who you are. Let me show you how this works from scratch in Node.js. This was one of the most practical things I've built in the ChaiCode Web Dev Cohort 2026. What Does Authentication Mean?…