First Last thinks this is interesting: Cluster is a set of ElasticSearch nodes that work together to handle the load bigger than single instance can handle (both in terms of handling queries and documents). From Introducing ElasticSearch from Mastering ElasticSearch by Marek Rogoziński, Rafał Kuć Publisher: Packt Publishing Released: October 2013 Note Clusters are like physical servers/machines Share this highlight http://www.safaribooksonline.com/a/mastering-elasticsearch/41349/ Twitter Facebook Google Plus Email Get Instant Access Now Start a Free Trial Learn about Safari for Business Have an account? Sign in. Minimise Unlock the rest of Mastering ElasticSearch and 30,000 other books and videos By clicking this box, you confirm that you have read and agree to the terms and conditions of our Membership Agreement, and you understand that when your trial period ends, you will be required to provide billing information if you wish to continue using the service. Unlock the rest of this book Start a Free 10-Day Trial loading Learn about Safari for Business Have an account? Sign in.