Windows Update web app Windows Update was introduced as a
web app with the launch of
Windows 98 and offered additional
desktop themes,
games,
device driver updates, and optional components such as
NetMeeting.
Windows 95 and
Windows NT 4.0 were retroactively given the ability to access the Windows Update website and download updates designed for those operating systems, starting with the release of
Internet Explorer 4. 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. Fixes to Windows 98 to resolve the
Year 2000 problem were distributed using Windows Update in December 1998. Microsoft attributed the sales success of Windows 98 in part to Windows Update. The Windows Update web app requires either
Internet Explorer or a third-party
web browser that supports the
ActiveX technology. The earliest version of the web app, version 3, does not send any personally identifiable information to Microsoft. Instead, the app downloads a full list of every available update and chooses which one to download and install. But the list grew so large that the performance impact of processing became a concern. Arie Slob, writing for the Windows-help.net newsletter in March 2003, noted that the size of the update list had exceeded , which caused delays of more than a minute for
dial-up users. Windows Update v4, released in 2001 in conjunction with
Windows XP, changed this. This version of the app makes an inventory of the system's hardware and Microsoft software and sends them to the service, thus offloading the processing burden to Microsoft
servers. An analysis done by security researcher
H. D. Moore in early 1999 was critical of this approach, describing it as "horribly inefficient" and susceptible to attacks. In a posting to
BugTraq, he explained that, "every single Windows 98 computer that wishes to get an update has to rely on a single host for the security. If that one server got compromised one day, or an attacker cracked the [Microsoft] DNS server again, there could be millions of users installing
trojans every hour. The scope of this attack is big enough to attract crackers who actually know what they are doing..." Microsoft continued to promote the tool through 1999 and the first half of 2000. Initial releases of
Windows 2000 shipped with the tool. The tool did not support Windows 95 and Windows NT 4.0.
Automatic Updates in
Windows XP Service Pack 1|alt=
Automatic Updates is the successor of the Critical Update Notification Utility. It was released in 2000, along with
Windows Me. It supports Windows 2000 SP3 as well. Unlike its predecessor, Automatic Updates can download and install updates. 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. The user can choose from three notification schemes: being notified before downloading the update, being notified before installing the update, or both. If new updates are ready to be installed, the user may install them before turning off the computer. A shield icon will be displayed on the
Shutdown button during this time. Windows XP and Windows 2000 SP3 include
Background Intelligent Transfer Service, a
Windows service for transferring files in the background without user interaction. As a system component, it is capable of monitoring the user's Internet usage and throttling its own bandwidth usage in order to prioritize user-initiated activities. The Automatic Updates client for these operating systems was updated to use this system service. 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 that allowed the user to restart immediately or dismiss the dialog box, which would reappear in ten minutes; a behavior that
Jeff Atwood described as "perhaps the naggiest dialog box ever." In 2013, it was observed that shortly after the
startup process, Automatic Updates (wuauclt.exe) and Service Host (
svchost.exe) in Windows XP would claim 100% of a computer's CPU capacity for extended periods of time (between ten minutes to two hours), making affected computers unusable. According to Woody Leonhart of
InfoWorld, early reports of this issue could be seen in
Microsoft TechNet forums in late May 2013, although Microsoft first received a large number of complaints about this issue in September 2013. The cause was an
exponential algorithm in the evaluation of superseded updates, which had grown large over the decade following the release of Windows XP. Microsoft's attempts to fix the issue in October, November and December proved futile, causing the issue to be escalated to the top priority.
Windows Update Agent in
Windows Vista|alt= Starting with
Windows Vista and
Windows Server 2008,
Windows Update Agent replaces both the Windows Update web app and the Automatic Updates client. It is in charge of downloading and installing software update from Windows Update, as well as the on-premises servers of
Windows Server Updates Services or
System Center Configuration Manager. Windows Update Agent can be managed through a
Control Panel applet, as well as
Group Policy,
Microsoft Intune and
Windows PowerShell. It can also be set to automatically download and install both
important and
recommended updates. In prior versions of Windows, such updates were only available through the Windows Update website. Additionally, Windows Update in Windows Vista supports downloading
Windows Ultimate Extras, optional software for Windows Vista Ultimate Edition. Unlike Automatic Updates in Windows XP, Windows Update Agent in Windows Vista and Windows 7 allows the user to postpone the mandatory restart (required for the update process to complete) for up to four hours. The revised dialog box that prompts for the restart appears under other windows, instead of on top of them. However, standard user accounts only have 15 minutes to respond to this dialog box. This was changed with
Windows 8: Users have 3 days (72 hours) before the computer reboots automatically after installing automatic updates that require a reboot. Windows 8 also consolidates the restart requests for non-critical updates into just one per month. Additionally, the login screen notifies them of the restart requirements. Windows Update Agent makes use of the
Transactional NTFS feature introduced with Windows Vista to apply updates to Windows system files. This feature helps Windows recover cleanly in the event of an unexpected failure, as file changes are committed
atomically. Since
Windows 8, the Windows Update is able to offers device firmware updates, for example
UEFI.
Windows 10 contains major changes to Windows Update Agent operations; it no longer allows the manual, selective installation of updates. All updates, regardless of type (this includes hardware drivers), are downloaded and installed automatically, and users are only given the option to choose whether their system would reboot automatically to install updates when the system is inactive or be notified to schedule a reboot. Microsoft offers a diagnostic tool that can be used to hide troublesome device drivers and prevent them from being reinstalled, but only after they had already been installed and then uninstalled without rebooting the system. Windows Update Agent on Windows 10 supports
peer-to-peer distribution of updates; by default, systems'
bandwidth is used to distribute previously downloaded updates to other users, in combination with Microsoft servers. Users may optionally change Windows Update to only perform peer-to-peer updates within their
local area network. Windows 10 also introduced cumulative updates. For example, if Microsoft released updates KB00001 in July, KB00002 in August, and KB00003 in September, Microsoft would release cumulative update KB00004, which packs KB00001, KB00002, and KB00003 together. Installing KB00004 will also install KB00001, KB00002 and KB00003, mitigating the need for multiple restarts and reducing the number of downloads needed. KB00004 may also include other fixes with their own KB number that were not separately released. A disadvantage of cumulative updates is that downloading and installing updates that fix individual problems is no longer possible. KB stands for knowledge base, as in
Microsoft Knowledge Base.
Windows Update for Business Windows Update for Business is a term for a set of features in the
Pro, Enterprise and Education editions of Windows 10, intended to ease the administration of Windows across organizations. It enables IT pros to: • Switch between the standard and the deferred
release branches of Windows 10. This feature has since been removed as Microsoft retired the deferred branch. • Defer automatic installation of ordinary updates for 30 days. Starting with Windows 10 version 20H1, this feature is more difficult to access. • Defer automatic installation of Windows upgrades (a.k.a. "feature updates", "cumulative updates") for 1 year. Starting with Windows 10 version 20H1, these updates are no longer automatically offered. You had to click on "Check for updates" to get the feature update or cumulative update. They are intended for large organizations with many computers, so they can logically group their computers for gradual deployment. Microsoft recommends a small set of pilot computers to receive the updates almost immediately, while the set of most critical computers receives them after every other group has done so, and has experienced their effects. Other Microsoft update management solutions, such as
Windows Server Update Services or
System Center Configuration Manager, do not override Windows Update for Business. Rather, they force Windows 10 into the "dual scan mode". This can cause confusion for administrators who do not comprehend the full ramifications of the dual scan mode. ==Complementary software and services==