Calendar

Calendar is a personal calendar application made by Apple Inc. that runs on both the OS X desktop operating system and iOS mobile operating system. It offers online cloud backup of calendars using Apple's iCloud service, or can synchronise with other calendar services, including Google Calendar and Microsoft Exchange Server. The OS X version was known as iCal before the release of OS X Mountain Lion in July 2012. ... iCal was the first calendar application for OS X to offer support for multiple calendars and the ability to intermittently publish/subscribe to calendars on WebDAV servers. [Calendar (Mac OS). Wikipedia]