Redis is a open-source, networked data structure server.

Redis is unlike others – It is single-core in-memory data store. It provides a rich interface to common data structures, but it is really designed to support those data structures for one local process or a set of processes on the same local host. It is not a distributed store. When the durability of data is needed, the in-memory nature of Redis allows it to perform extremely well compared to database systems that write every change to disk before considering a transaction committed.

Thanks to Redis our applications performs well on complex data structures.