What is Redis?

Redis (Remote Dictionary Server) is an open-source, in-memory data structure store used as a database, cache, message broker, and queue. It was created by Salvatore Sanfilippo in 2009 and is now maintained by Redis Ltd. Redis stores all data in RAM, which makes reads and writes extremely fast — typically under a millisecond. It supports a wide variety of data structures including strings, lists, sets, sorted sets, hashes, streams, bitmaps, and HyperLogLogs, going far beyond a simple key-value store. It is one of the most popular tools in modern backend architecture for caching, session storage, and real-time processing.