Redis is an open-source, in-memory data structure store that can be used as a database, cache, and message broker. It supports a wide range of data structures such as strings, hashes, lists, sets, and sorted sets. Redis is known for its speed and efficiency due to the fact that it stores all data in RAM instead of on disk. This makes it a popular choice for high-performance applications where fast read and write operations are critical. Additionally, Redis provides advanced features such as transactions, pub/sub messaging, Lua scripting support, and automatic failover for high availability.
