These are a group of UI utilities that give information about the core level. On selecting a Core in the dropdown, you will see the following screens:

• Overview: This will display some of the basic metadata about the running Solr core. You can add a file admin-extra.html, which consists of additional information if you would like to display in the Admin Extra block.
  
• Ping: This lets you send a ping to the selected core to determine whether the core is active or not.
• Plugins / Stats: Shows all the plugins installed and statistics. The performance factor of the Solr cache can be checked here.

• Segments info: This lets you see visualizations of different segments by Lucene for the core selected. It shows information about the size of each segment, with units in both bytes and number of documents. You can also check out the number of deleted documents.