Windows Update is a service provided by Microsoft that provides updates for the Microsoft Windows operating system and its installed components, including Internet Explorer.
An optional feature disables access to Windows Update and enables access to Microsoft update, an expanded version of the service which provides updates not just for the operating system & Internet Explorer, but also for other Microsoft Windows software, such as Microsoft Office, Windows Live applications, and Microsoft Expression.
Security updates are delivered on the second Tuesday of each month, called “Patch Tuesday,”
but security updates can be delivered whenever a software update is required to prevent an exploit targeting Windows users.
Windows Update can be configured to install updates automatically, ensuring that a computer is always up-to-date and not vulnerable to computer worms and other malware.
Windows Vista, Windows Server 2008 and the most recent Windows 7 provide a Control Panel to configure update settings and check for updates.
For previous versions of Microsoft Windows, updates can be downloaded from the Windows Update website, using Internet Explorer.