How Redis Caching Actually Works — A Visual Guide...

TL;DR: Redis caching sits between your application and database, storing frequently accessed data in memory for sub-millisecond reads. This guide walks through cache-aside, write-through, and write-behind patterns with diagrams, working Node.js code, and real-world lessons from building a stock trading platform handling 100K+ concurrent users. The Problem Your API is slow. Users are waiting 200-500ms for responses that hit the database every single time. Your PostgreSQL instance is sweating unde