Hello readers 👋, welcome to the 8th blog of our Node.js journey!

So far, we've covered how Node.js works under the hood, its event loop, non-blocking code, and how to handle async operations. Now we're going to build something practical that almost every real-world application needs: user authentication using JSON Web Tokens (JWT) .

Authentication is how an application knows who you are. You see it every day: logging into a website, accessing private messages, or making a purchase. Today, we'll understand what JWT is, how it works (without diving into complex cryptography), and how to implement a simple, secure login flow in Node.js.

Let's get started.

What authentication means

Authentication is the process of verifying a user's identity. When you log in with a username and password, the server checks those credentials and, if they match, it should remember that you are authenticated for subsequent requests.…