lightbulbBook reference: Xu, System Design Interview. Original notes kept below; rewrite them in your own words.
5.2.1 Redis
In-memory store for caches and queues.
Why it matters
Production systems depend on this idea. Learn the vocabulary and the failure modes before you wire tools.
How it is used
Start with the simplest correct approach. Measure. Add complexity only when load or correctness demands it.