Windows Update is a Microsoft service for the Windows 9x and Windows NT families of operating system, which automates downloading and installing software updates over the Internet.
The service delivers software updates for Windows, as well as the various Microsoft antivirus products, including Windows Defender and Microsoft Security Essentials.
The initial focus of Windows Update was free add-ons and new technologies for Windows.
Security fixes for Outlook Express, Internet Explorer and other programs appeared later, as did access to beta versions of upcoming Microsoft software, e.g., Internet Explorer 5.
Microsoft routinely releases updates on the second Tuesday of each month (known as the Patch Tuesday), but can provide them whenever a new update is urgently required to prevent a newly discovered or prevalent exploit.Automatic Updates in Windows XP gained notoriety for repeatedly interrupting the user while working on their computer.Every time an update requiring a reboot was installed, Automatic Updates would prompt the user with a dialog box.The scope of this attack is big enough to attract crackers who actually know what they are doing..." Automatic Updates is the successor of the Critical Update Notification Utility. Instead of the five-minute schedule used by its predecessor, Automatic Updates checks the Windows Update servers once a day.After Windows ME is installed, a notification balloon prompts the user to configure the Automatic Updates client.