A file with the extension of the M4B file is a MPEG-4 Audio Book file. They’re used by iTunes to save audiobooks.
Some media players use the M4B format to save digital bookmarks with the audio. Also, it enables you to pause playback and then resume later. It’s the main reason they’re preferred over MP3s. As it can’t store your place in the file.
The audio format of M4A is quite similar to M4B except for those types of files that are used for music rather than audiobooks.
Apple’s iPhone also uses MPEG-4 Audio format. But those files are saved with the extension of M4R.
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Do You Want To Open M4B File On iPhone?
iTunes is the main program used to play M4B files on a PC to transfer audiobooks to an iPhone or another iOS device. You can also do this after adding the audiobooks to iTunes and then syncing your device via iTunes.
Initiate by moving the M4B file to iTunes. However, in Windows, simply use the File menu to select either Add File to Library… or Add Folder to Library… to browse the M4B file. On Mac, head over to File > Add to Library…
With the device connected in, tap or click the phone icon in iTunes to switch the window to the iOS device. Select the Audiobooks menu located on the left side of iTunes. Place a checkmark to Sync Audiobooks. You can then choose whether you like to sync all the audiobooks from your iTunes library or just certain ones.
You can now sync your device via iTunes to send an M4B file to iOS devices.
Open An M4B File On PC:
iTunes is not the only program that plays an M4B file on a PC. Windows Media Player also works but you probably have to open Windows Media Player first. You can then open the M4B file from WMP’s menu since Windows might not recognize the extension of M4B.
Other multi-format media players that support the same M4A format, such as MPC-HC, VLC, and PotPlayer, will also play M4B files.
Tip: M4B audiobook that you buy is likely secured by DRM. It means that it’ll only play using authorized PC software and devices. For instance, some M4B based audiobooks that you buy from the iTunes store are DRM protected and can play only in iTunes and devices authorized through iTunes.
Procedure To Convert M4B File
Well, M4B files are audiobooks, they’re quite large and best converted with a dedicated, offline free file converter program. DVDVideoSoft’s Free Studio is a free M4B file converter that saves the M4B to MP3, WMA, M4R, WAV, FLAC, and other audio formats.
Zamzar is another amazing M4B converter but it runs on your browser. It means that you have to upload the file to their website to have it converted. Also, it converts M4B to MP3 online, as well as to the same formats such as M4A, AAC, and OGG.
Note: You can’t usually modify a file extension to one that your PC recognizes and expect the newly renamed file to be usable. However, the real file format conversion using one of the procedures mentioned above must take place in some situations.
How To Make An M4B File
If you wish to put an audiobook on your iPhone, but the audio file is not in the M4B format. Then you’ll have to change the MP3, WAV, or any format the file is in, to M4B so that the iPhone can’t mistake it for a song.
Audiobook Binder can also convert MP3 to M4B on macOS. Windows users can also install MP3 to iPod/iPhone Audio Book Converter to convert different MP3s to M4B files or merge the MP3s into one big audiobook.
Conclusion:
Here’s a complete guide on M4B. If you know any other method to convert files then let us know below. Stay tuned with us!
Till then! Stay Happy 
Also Read:
Avdshare Audio Converter is a professional M4B to iPhone converter working to convert any M4B file to iPhone device best supported MP3, AAC, etc.
Epubor works as a professional M4B DRM protection removal software that can easily remove the M4B DRM protection and at the same time gives MP3 as the output file.