Authentication & Authorization — Prerequisites

What You Need Before Starting

1. Basic Express (required)

Routes (app.get, app.post), the middleware pipeline ((req, res, next)), and how req/res carry data through a request. Every code example in this technology — session middleware, JWT verification, route protection — is written as Express middleware, so if the middleware chain and next() contract aren't already comfortable, this platform's own Express.js technology is the right place to start first.

2. Basic understanding of HTTP cookies/headers (recommended, not required)

Knowing that a cookie is a small piece of data the browser stores and automatically re-sends to the same domain, and that headers like Authorization carry data explicitly attached per request, helps the sessions-vs-tokens material land faster. This isn't assumed in depth — the Fundamentals tab explains cookies from first principles before relying on them.

3. What you do *not* need yet

Quick self-check

Can you explain, without looking it up, what happens if a piece of Express middleware never calls next() and never sends a response? (The request hangs forever — Express is waiting indefinitely for one of those two things to happen.) If that's unclear, spend time with this platform's Express.js Fundamentals tab first — the auth middleware in this course builds directly on that contract.