Redis

The fastest way to learn Redis is to run it and play with redis-cli yourself.

The String is the simplest, most-used type — it powers caches, counters, and locks.

The feature that makes Redis an ideal cache: keys can expire and self-delete.

Redis's real power is its rich structures — picking the right one solves half the problem.

Bitmaps, HyperLogLog, and Streams solve huge problems with tiny memory — knowing them sets you apart.

Redis isn't just a cache — you can build real-time messaging between services in two lines.

When several commands must run as one unit without interleaving, transactions and Lua are the answer.

Caching is Redis's most common use — but done wrong it causes stale data or a database meltdown.

Redis lives in memory — a crash loses everything unless you configure disk persistence right.

Memory is limited and expensive — you must know how Redis behaves when memory fills up.

A single Redis node is a single point of failure — replication and Sentinel keep you running if it dies.

When data outgrows one node's memory, Redis Cluster shards it across nodes automatically.

In distributed systems you must stop two processes from touching the same resource — Redis excels here, carefully.

An exposed, unprotected Redis is a security disaster — and production needs sharp performance monitoring.