When an appointment or meeting is marked private, other people cannot see details of the item. This includes people who have delegate access rights or other people who you have granted read permissions to your calendar.
Details of a private item can also be blocked from appearing when your calendar is printed.
Create or open the appointment or meeting that you want to mark as private.
On the Appointment or Meeting tab, in the Tags group, click Private.
The Private command is not available for a single occurrence of a recurring appointment or meeting. You can, however, mark the entire series as private.
Important: You should not rely solely on the private command to prevent other people from accessing the details of your appointments, contacts, or tasks. To ensure that other people cannot read the items that you mark as private, do not grant them Read permission to your Calendar, Contacts, or Tasks folders.
To remove the privacy mark from an appointment or meeting, click on the appointment, and then on the Calendar Tools tab, click Private. Calendar items marked as private include a lock icon in Calendar or Preview view.