The description of mobi format expansion
The mobi file is an electronic book saved via the MOBI algorithm, an extension primarily applied by the Mobipocket Reader but nowadays supported by a variety of readers. It contains an eBook and can incorporate DRM copyright protection for unauthorized viewing or copying prevention. MOBI files are handled by a multitude of different desktop computer applications, PDAs, tablets and eReaders.
Amazon’s new Kindle Format 8 (KF8) is closely related to the MOBI format. KF8 supports many new layout and formatting options, including embedded fonts and CSS3 and HTML5 content. KF8-formatted e-Books are distributed and saved as mobi or as azw3 files, depending on the gadget which handles the electronic book. Amazon company currently possesses all the rights onto the MOBI format. Amazon’s electronic formats, including AZW3, AZW1 and AZW apply the MOBI format but handle a proprietary DRM scheme.
NOTE: Mobipocket eBooks also use the PRC extension.