Calendar

Calendar (previously iCal before Mac OS X 10.8) is a personal calendar application made by Apple that runs on the Mac OS X operating system. iCal was the first calendar application for Mac OS X to offer support for multiple calendars and the ability to publish/subscribe calendars to WebDAV server.

Release history
Apple licensed the "iCal" name from Brown Bear Software, who used it for their own unrelated iCal application since 1997.

Apple's first release of iCal was a free download for Mac OS X 10.2 on September 10, 2002. With the release of Mac OS X 10.3, it was bundled with the operating system as iCal 1.5. Version 2 of iCal was released as part of Mac OS X 10.4, Version 3 as part of Mac OS X 10.5, Version 4 as part of Mac OS X v10.6, and Version 5 as part of Mac OS X 10.7. With 10.8, it was renamed "Calendar".

iCal development is quite different from other Apple software because it was designed independently by a small French team working "secretly" in Paris, led by Jean-Marie Hullot, a friend of Steve Jobs. iCal's development has since been transferred to Apple's U.S. headquarters in Cupertino.