Topics allow you to tag individual appointments with a pre-defined topic.
While in Admin, go to the Appointments menu and navigate to Options.
Enable Topics by checking the Enable Topics setting.
Once enabled you can specify the following:
Allow multiple Topics to be selected - This will allow multiple topics to be included in a single appointment.
Topics Required - This setting will force users to select a topic before confirming an appointment.
Navigate to Topics + to Create. Actions column to Edit or Delete topics.