JWT
A digital ID card your app uses to remember you're logged in.
What is JWT?
JWT (JSON Web Token) is a small encrypted token stored in your browser. After you log in, your app gives you a JWT. Every request you make includes it so the server knows who you are without asking you to log in again.
Think of a JWT like a wristband at a concert. After the bouncer checks your ticket once, the wristband lets you come and go without being checked again.
In Vibe Coding
Supabase uses JWTs automatically. When a user logs in, Supabase generates a JWT and stores it in the browser. Every time your app calls Supabase, that JWT is sent along to prove who the user is.
Example
For example: You log into an app at 9am. The app stores a JWT in your browser. When you come back at 2pm, the JWT is still there — so you're still logged in without re-entering your password.