While researching NoSQL databases recently, I stumbled upon Riak, found myself intrigued, and decided to dive a little deeper. The quick and dirty: Riak is a key-value, distributed database made up of multiple independent nodes which can be joined together to form Riak clusters. Generally, when data is written into a Riak cluster, it will be written to multiple nodes so that even if a single node does go down, the data will still be reachable. One of Riak's trademarks is this focus on high availability.
via NoSQL databases