When I first learned about JSON Web Tokens (JWTs), I thought I had authentication figured out. The tutorial showed me this simple line: localStorage . setItem ( ' token ' , jwt ); Enter fullscreen mode Exit fullscreen mode If you're currently storing tokens this way, don't worry, most tutorials teach this approach. But once you understand the risk, there's a much safer way to handle it. Let's break it down together. What Is a JWT, Really? Think of a JWT as a temporary ID badge. When you log in, the server gives you this badge. You show it on every request to prove who you are. The badge contains three parts: Header: What type of badge it is Payload: Your user ID, permissions, expiration time Signature: Proof the badge is genuine (created by the server) Here's what a JWT looks like: eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJ1c2VySWQiOiIxMjM0NSIsImlhdCI6MTUxNjIzOTAyMn0.SflKxwRJSMeKKF2QT4fwpMe... Enter fullscreen mode Exit fullscreen mode That long string is your key to the application.…