What is JWT (JSON Web Token)?
TL;DR: JWT is a compact, URL-safe token format used for securely transmitting information between parties. It's the standard for authentication in modern web applications — when you log in, the server issues a JWT that proves your identity.
A JWT has three parts separated by dots: Header (algorithm), Payload (claims/data), and Signature (verification). The payload is Base64-encoded (not encrypted) — anyone can read it, but only the server can create a valid signature.