MPEG-4 Audio Book File
M4B is used to store bookmarked files often used by QUickTime and the Windows Media Player, the M4B files is used together with the MPEG-4 file which contains the Audio.
Using these bookmarks it is possible with QuickTime to transfer files amongst various devices so that they can be shared and can be used for Audio books and Podcasts.
Advantages of this format is dependent on the software used for example with QuickTime various video formats and codecs can be used including H.264
With Windows Media Player audio fingerprinting can be used as is the capability to copy multimedia disc to hard drive, the use of lossless codecs and the organization of multimedia files.