Contacts in a calendar appointment

I've noticed that I can add contacts to a calendar appointment. What is this useful for? Will they be notified of the appointment? What can they do with the appointment? What is the whole purpose? I can invite contacts to attend, so I don't see what this is used for.


Solution 1:

Adding contacts will send automatic email invitations. The contacts can accept the invitation and the appointment will appear in their own calendar(s).