The first version of WSUS was known as Software Update Services (SUS). It only delivered hotfixes and patches for Microsoft operating systems. SUS ran on a Windows Server operating system and downloaded updates for the specified versions of Windows from the remote Windows Update site, operated by Microsoft. The clients could then download updates from this internal server, rather than connecting directly to Windows Update. Support for SUS by Microsoft was originally planned to end on December 6, 2006, but based on user feedback, the date was extended to July 10, 2007.
WSUS builds on SUS by expanding the range of software it can update. The WSUS infrastructure allows automatic downloads of updates, hotfixes, service packs, device drivers and feature packs to clients in an organization from a central server(s). This saves bandwidth, time and disk space, as the individual computers in a network do not have to connect to an external server themselves, but connect to a local central server. It also increases administrators' control and allows clients to obtain updates in environments that do not have internet access.
