Redis stands for REmote DIctionary Server. By default, redis stores all data in memory. It's a key-structure database. redis-server is the actual datastore. redis-cli is the command line interface that performs any redis command. By default, redis binds to port 6379.

Starting the redis server

redis-server

While you can build a complete system using Redis only, I think most people will find that it supplements their more generic data solution - whether that be a traditional relational database, a document-oriented system, or something else. It’s the kind of solution you use to implement specific features.