Visitors tab: what are the options to display crawlers' visits at the "Visitors Tab"?

The "Visitors Tab" provides the following options for site users to filter the crawlers' visits results: "List by visitor", "List by each visit" and "List crawler visits". These options displayed at the bottom of the "Visitors Tab" page. 

Also, users can hide visitors information by clicking on [ Hide this visitor ] in the Action column. To restore a hidden visitor's visibility click on List excluded visitors button (at the bottom of the page), find an IP of a hidden visitor you want to make visible again and click on [ Remove this visitor ].