Riak is a distributed NoSQL key-value data store that offers extremely high availability, fault tolerance, operational simplicity and scalability. In addition to the open-source version, it comes in a supported enterprise version and a cloud storage version that is ideal for cloud computing environments. Riak implements the principles from Amazon's Dynamo paper with heavy influence from Dr. Eric Brewer's CAP Theorem. Written in Erlang, Riak has fault tolerance data replication and automatic data distribution across the cluster for performance and resilience. Riak CS is an object storage layer that sits on top of the Riak key-value platform. The open source Riak CS can be upgraded to Riak CS Enterprise, the commercial-grade and supported version.