Acronym: Advanced Streaming Format (Later renamed Advanced Systems Format)
Introduced by/when: For the Windows Media Framework
Extension: WMA or WMV
Used: The format does not specify how the video or audio should be encoded, but instead just specifies the structure of the video/audio stream. What this means is that ASF files can be encoded with basically any audio/video codec and still would be in ASF format. This is similar to the function performed by the QuickTime, AVI, or Ogg formats. Files containing only WMA audio can be named using a .wma extension, and files of only audio and video content may have the extension .wmv. Both may use the .asf extension if desired.