Windows Update

Windows Update is a free updating service by Microsoft that regularly give updates to Windows and other Microsoft products, sometimes also for drivers. It is used to keep Microsoft apps and the Windows operating systems updated and often protected from malware and ransomware.

Windows XP, Server 2003 and earlier
Windows Update was launched as a web service using Internet Explorer technologies with the release of Windows 98. Previously, it was included since build 1351 as "Internet System Update". It was ported to the NT line of Windows with the Windows 2000 Beta 3.

It works by installing an ActiveX control element, which allows installing updates directly from Internet Explorer. The web service for Windows 98 and Me was shut down in the early 2010s, while Windows 2000 was updated to use Windows XP's web service, which itself was shut down in 2019 due to Microsoft being updating their security to use the SHA-256 algorithm, which is not supported by Windows versions earlier than Vista. All released updates for Windows, Office and other Microsoft products are still available at the Microsoft Update Catalog.

Windows Vista, Server 2008 and later
In Windows Vista (since build 5259), Windows Update was overhauled to have an own Control Panel applet, rather than being based on a web service. In Windows 10, Windows Update was moved to the Settings app.

Location

 * In Windows 98 through to XP, it is located in Internet Explorer.
 * In Windows Vista through to 8.1, it is located in the Control Panel.
 * In Windows 10 through to 11, it is located in the Settings app.

Patch Tuesday
Patch Tuesday is a day where Microsoft releases patches and security updates for Windows routinely, usually being the second Tuesday of every month. However, Microsoft still releases urgent updates on most other days.

Automatic Updates
Formerly known as the Windows Critical Update Notification Tool in Windows 98 and 2000, this tool runs in the background and notifies the user when a critical update is available. In Windows Me (9x) and Windows XP / 2000 SP3 (NT), this tool was replaced with Automatic Updates. Automatic Updates will not require a web browser, and checks updates less routinely than the Critical Update Notification Tool.

Filetypes
On XP and earlier, updates were either packed in executables or in cabinet archives. Windows Vista uses    and   file extensions on the updates. Also, standalone updates are now packed in  archives, which are opened by. These archives still have updates packed in cabinet archives. Windows 11 additionally uses  files.

Windows 10 and 11 Feature Updates

 * See Microsoft Windows and Windows 11 updates for the subsequent feature updates released for Windows 10.