Redis is a distributed, in-memory, key-value store that provides high scalability, reliability, and performance. Redis is much more than a distributed cache; it stores not only key-value pairs but also collections such as lists, sets, sorted sets, maps, and many more. Redis also provides a set of algorithms that can be performed on those collections.

Redis supports scalability by enabling client-side sharing and server-side master/slave replication. Redis stores encoded data in memory, so a large amount of data can be stored with a minimal memory footprint. Redis can also be configured to write data to a file for fault tolerance based on the timing and frequency of data writing.