By adding security to a group type, you control the base security of every group of that type. Let's say your organization adds a new type of group to help manage some classes you're starting. You may want to create a new group type for this initiative where every class is a group of this new type. By adding security to the group type, you can ensure that every group can be viewed and edited by a select handful of people. To add security to a group type, go to Admin Tools > Settings > General > Group Types. There you will see a list of group types in a table. In the far right column, you will see a ti ti-lock button. Clicking this will allow you to set the security for the selected group type.