You can let other Office 365 users see whether or not you are free or busy for a particular time.

Outlook for Windows or Mac

1. Open Outlook
2. Click the Calendar icon at the bottom of the window
3. Right click the name of your calendar
4. Click Properties
5. Select Permissions
6. Send a sharing invitation with someone via email. You can choose how much access to allow and change access settings any time or choose "Inside your organization" to allow permissions

Outlook On The Web 

1. Login to https://office365.austin.utexas.edu/ 
2. Click the calendar icon
3. Right click your calendar name
4. Select Sharing and Permissions Send a sharing invitation via email. You can choose how much access to allow and change access settings any time or choose "Inside your organization" to allow permissions