# Redis
Confidence: high
Last verified: 2026-05-22
Generation: human_only


## TL;DR

Redis is an in-memory data structure store used as a database, cache, message broker, and streaming engine. It supports strings, hashes, lists, sets, sorted sets, bitmaps, hyperloglogs, geospatial indexes, and streams. Sub-millisecond latency, 100K+ ops/sec on modest hardware.

## Core Explanation

Persistence: RDB (point-in-time snapshots) and AOF (append-only file log). Pub/Sub for messaging. Lua scripting for atomic operations. Redis Sentinel for high availability. Redis Cluster for horizontal sharding (16384 hash slots). Common patterns: session store, rate limiter, leaderboard, distributed lock (Redlock).

## Further Reading

- [Redis Documentation](https://redis.io/docs/)