For each appointment, a notification is sent to you by email, text(SMS), or push. You can update your preferred method of contact in your profile.
The notification counter will show all of your unread messages. As you interact with a notification, the counter will decrease.
Each color means something different.
You can clear the messages one at a time or in groups by selecting the square next to the notifications you want to interact with. When you do you will have the option to mark them read, or delete them.