Calendars are used in Project Plan 365 to schedule your project and to identify working times to determine when resources in your organization are available to work on tasks in your project.

Typically, calendars are assigned to resources so that the application can track when resources are available to work on tasks to which they are assigned. Take into account that you need to set up calendars for your project before you can assign them to resources.

To define unique or specific exceptions for working time and non-working time, you can create a task calendar.