ASF (Advanced Streaming Format) is a file format that stores audio and video information, and it is specially designed to run on networks like the Internet.
This file format is a highly flexible and compressed format that contains streaming audio, video, slide shows, and synchronized events. When you use .asf files, content is delivered to you as a continuous flow of data. You no longer have to wait for your audio and video files to fully download before you start to view them. When an Audio Video Interleave (.avi) file is compressed and converted to an .asf file, the file begins playing after only a few seconds. The file can be unlimited in length and can run over Internet bandwidths.