What data structures does Redis support and when would you use each?

Redis supports: Strings (caching, counters), Lists (queues, timelines), Sets (unique items, tags), Sorted Sets (leaderboards, rate limiting), Hashes (objects, user sessions), Bitmaps (flags, bloom filters), HyperLogLog (cardinality estimation), Streams (event sourcing, logs). Use Strings for simple caching, Sorted Sets for ranked data with scores, Hashes for structured objects, Lists for FIFO queues. Pub/Sub enables messaging. Choose based on access patterns.