# What is Redis? — Redis

Source: https://www.geekswithgeeks.com/en/redis/redis-intro

> 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.