Cookie
Domain: Internet & Web
🎯 Motivation
Small pieces of data stored in the browser. Used for sessions, preferences, and tracking.
📋 Concrete Example
Cookie: user logs in. Server sets cookie: session_id=abc123. Browser stores it. Next request: browser sends the cookie. Server knows who the user is. No need to log in again.
🔗 Analogy
A cookie is like a name tag - the server gives you a name tag (cookie) on your first visit. Every time you return, you wear the name tag. The server recognizes you immediately.