A listener can often download software players (many, such as Windows Media Player and MusicMatch Jukebox, are free) which will play different types of audio files, such as MP3 and WMA.
Some vendors, such as Audible.com, who have a proprietary (non-standard or exclusive) file format will provide software which plays their content.
Other vendors, such as OverDrive, provide playback software that enhances the ability of users to interact with downloadable digital audio books. The audio book can be divided and tagged to enable nonlinear navigation through the book. Variable speed playback allows each user to speed up or slow down the playback without any change in pitch.