The macOS version was known as iCal before the release of OS X Mountain Lion in July 2012.

[1] iCal's initial development was quite different from other Apple software: it was designed independently by a small French team working "secretly" in Paris, led by Jean-Marie Hullot, a friend of Steve Jobs.

[3] Users can subscribe to other calendars so they can keep up with friends and colleagues, and other things such as athletic schedules and television programs, as well as set notifications for upcoming events either in the Notification Center,[4] by email, SMS, or pager.

[5] It is integrated with iCloud, so calendars can be shared and synced with other devices, such as other Macs, iPhones, iPads, iPod touch, and PCs over the internet.

Calendar support was added to CarPlay with iOS 13, allowing Siri to display and read out a user's upcoming events while driving.