Report Categories allow you to organize your Reports. There are three default Report Categories: Client, Installation, and Management. You can add/edit/delete Report Categories in the Report Explorer interface:
When you choose to create a new Report Category, the Add Category form will open for you to name the new Category and select the Reports that you want to be in the new Category:
The Reports that you add to the new Category will display when you click the [Other] button on the Reports tabs throughout SI 2016:
When you choose to edit a Category, the following form opens where you can check/uncheck reports: