How the web works under the hood: HTTP/1.1 vs HTTP/2/3, request headers, cookies & SameSite policies, CORS, JWT tokens, WebSockets, and browser security sandboxes.
What you'll practise: Inspect and replay requests with cURL and Postman; Examine cookies and security headers in DevTools; Decode a JWT and identify what it reveals; Test CORS and CSP behaviour on a practice site; Call REST and GraphQL APIs, then inspect WebSocket traffic.