If your calendar contains data that is confidential and/or should be kept for internal use only, it's important to keep your calendar secure so that only authorized users can access the data.
Here are some important reminders and tips to help you keep confidential information protected:
Use account-based access for calendar users. This is a more secure method of accessing the calendar, since each account is tied to a specific person, must be verified, and requires a log in to access the calendar.
Ensure that each user has appropriate access for their role: This means they can only access relevant sub-calendars and they have the appropriate permission level for each sub-calendar.
If you need to use shareable calendar links, add password protection to each link.
Regularly review all access points (both account-based users and shareable calendar links). Delete or remove any out-dated access points, and check permissions on active users/links to ensure they are at the appropriate level.
You can disable sharing options to prevent events from being shared as an event page, to another calendar, etc.