The tool then compares this list with the list of installed updates on its machine and displays an update availability notification.Once the check is executed, any custom schedule defined by the user is reverted to the default. Moore in early 1999 was critical of this approach, describing it as "horribly inefficient" and susceptible to attacks.Since its inception, Microsoft has introduced two extensions of the service: Microsoft Update and Windows Update for Business.
Service packs and feature updates are very large cumulative sets of updates that introduce new features or remove discontinued features.
System administrators can configure Windows Update to install critical updates automatically, so long as the computer has an Internet connection.
Windows 95 and Windows NT 4 were retroactively given the ability to access the Windows Update website, and download updates designed for those operating systems, starting with the release of versions of Internet Explorer 4.
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.