The Advanced Stream Redirector (ASX) file format is a type of XML-based metafile used by Microsoft's Windows Media Player. It contains a list of URLs pointing to streaming media files, such as audio and video content. Instead of containing the actual media data, the ASX file acts as a playlist or shortcut, directing the media player to the location of the streaming content on a server. This allows for efficient streaming, as the player only needs to download the ASX file initially, which is typically small in size, and then stream the media content from the specified URLs. ASX files can also include metadata about the media, such as title, author, and copyright information. They are commonly used for streaming radio stations, video broadcasts, and other online media content. The format supports various streaming protocols, including MMS (Microsoft Media Server) and HTTP. While largely superseded by more modern streaming technologies, ASX files remain compatible with older versions of Windows Media Player and may still be encountered in legacy systems or specific streaming scenarios.