Redis is an ultra-fast database technology typically used for database caching. It's main difference from a traditional database is that it stores data on RAM as opposed to something like a Hard Drive. This means that data retrieval is ultra-fast. Additionally, Redis can be used for sending messages across data channels. This is the main use that RC takes advantage of! By moving messaging into a separate system we allow plugin messaging channels to remain clear for other uses.

You can set up a small, free, Redis server here! It's worth noting that the free Redis plan is not going to be suitable for larger networks. But chances are, if you're a larger network, you can certainly afford the cost of a higher-end Redis server.