HBase should be used when the big data application has:  A variable schema  When data is stored in the form of collections.  If the application demands key-based access to data while retrieving.  And the essential components of Hbase are:  Region- This component contains a memory data store and Hfile.   Region Server-This monitors the Region.   HBase Master- It is responsible for monitoring the region server.   Zookeeper- It takes care of the coordination between the HBase Master component and the client.   Catalog Tables-The two important catalog tables are ROOT and META.ROOT table tracks where the META table is, and META table stores all the regions in the system.