Lesson 1 / 18

What is Redis?

An in-memory key-value store, and where it fits in a real system.

In-memory key-value store

Redis (REmote DIctionary Server) keeps data in RAM instead of on disk, so reads and writes happen in microseconds — often 50-100x faster than a traditional database.

Common use cases

Caching, session storage, real-time leaderboards, rate limiting, pub/sub messaging, and job queues — anywhere speed matters more than complex querying.

Whiteboard vs filing cabinet

A disk database is a filing cabinet — reliable, huge capacity, slower to reach. Redis is the whiteboard on your desk — instantly readable, but wiped if the power's out unless you save a copy.