The Dynamics 365 calendar displays appointments and service activities that originated in Dynamics 365. It offers Day, Week, and Month views. You also have the option to create Activities and records directly from the ribbon above the calendar.
The calendar in Dynamics 365 looks and feels just like the one in Outlook, and since many organizations use Outlook (or something similar), the one in Dynamics 365 is rarely used. Instead, many organizations use Server-Side Synchronization with Account, Contact, Appointments, and Tasks synchronization enabled, which auto-syncs Dynamics 365 appointments and task activities to Outlook calendars.
Just as in Outlook, an appointment can be opened directly from the calendar by double-clicking on the entry. Day, Week, and Month views are shown below.