# What is Redis? — Redis Fundamentals: Caching, Data Structures and Persistence

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

> Learn what Redis is, why in-memory storage is fast and where it fits alongside a traditional database.

## In-memory key-value store

**Redis** (REmote DIctionary Server) keeps data in RAM instead of on disk, so reads and writes typically take microseconds to under a millisecond, far faster than a disk-based 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.