The ZooKeeper framework was originally built at “Yahoo!” to access their applications robustly.

Later zookeeper was open-sourced to apache community

ZooKeeper is a central service to maintain configuration information, naming, and synchronisation, and provides group services.

All these zookeeper services are used in some form or another by many distributed applications.

Apache ZooKeeper architecture contains Client–Server in which clients are machines and servers are nodes.

Today apache zookeeper is generally used to manage the Hadoop cluster.

Zookeeper provides Reliability, Scalability and Transparency to Distributed Applications.