Windows Calendar

Windows Calendar is the default calendar app in Windows Vista, Windows 8/8.1, Windows 10 and Windows 11.

16-bit Windows
Windows Calendar is included in Windows versions 1.0 to 3.11. It has been replaced in both Windows for Workgroups 3.1 with Schedule+, which is also included in Windows NT 3.x.

Windows 95
Windows 95 and Windows NT 4.0 do not ship with a calendar application and this continues all the way up to Windows XP, while Schedule+ has been shifted to Office 95 and turned into a 32-bit application.

Windows Vista
Windows Calendar was first introduced in Windows Vista build 5212, although it is mostly not functional in this build. In Windows Vista build 5231, it received an updated toolbar and the tasks pane was added. The Preferences page was also added as well where it contains various settings such as first day of the week and default appointment length. The app also received an updated icon. The UI of Windows Calendar would be completely revamped in Windows Vista build 5259 but the Publish to RSS feature was removed. Build 5270 would re-add the toolbar. Windows Vista build 5355 would revamp the UI again with many new options being added to the toolbar and the bottom toolbar was removed. Build 5466 would later add a delete button to the toolbar. The icon would be updated to its RTM form in build 5840.16389.

Windows 7
Although Windows Calendar was removed from Windows 7 in favor of the built-in calendar functionality in Windows Live Mail, it can be added back to Windows 7 by copying the program files from Windows Vista.

Windows 8
Windows Calendar was brought back in Windows 8/8.1, but in Metro language form.

Windows 10
The Calendar app from the original release had some changes, but mostly follows the same Metro language design as its 8/8.1 counterpart. A later update (2017 or 2018) replaced Metro with the Fluent Design language.

It is bundled with Windows Mail. Therefore, removing Windows Calendar will also remove Windows Mail as well and vice versa.