Windows Media Services (WMS) is a software component of Microsoft Windows Server that allows an administrator to generate streaming media (audio/video). Only Windows Media, JPEG, and MP3 formats are supported.
In addition to streaming, WMS also has the ability to cache and record streams, enforce authentication, impose various connection limits, restrict access, use multiple protocols, generate usage statistics, and apply forward error correction (FEC). It can also handle a high number of concurrent connections making it ideal for content providers. Streams can also be distributed between servers as part of a distribution network where each server ultimately feeds a different network/audience. Both unicast and multicast streams are supported (multicast streams also utilize a proprietary and partially encrypted Windows Media Station (*.nsc) file for use by a player.) Typically, Windows Media Player is used to decode and watch/listen to the streams, but other players are also capable of playing Windows Media content (VLC, MPlayer, etc.)
64-bit versions of Windows Media Services are also available for increased scalability. The Scalable Networking Pack for Windows Server 2003 adds support for network acceleration and hardware-based offloading, which boosts Windows Media server performance. The newest version, Windows Media Services 2008, for Windows Server 2008, includes a built-in WMS Cache/Proxy plug-in which can be used to configure a Windows Media server either as a cache/proxy server or as a reverse proxy server so that it can provide caching and proxy support to other Windows Media servers. Microsoft claims that these offloading technologies nearly double the scalability, making Windows Media Services the industry's most powerful streaming media server.