The MOBI file format stands as a hallmark in the history of e-readers, originating from the earlier PalmDOC format. Its journey commences with the acquisition of the French company Mobipocket by Amazon in 2005. The MOBI format, which became widely associated with Kindle devices, has the distinctive feature of incorporating both the old MOBI data as well as carrying newer KF8 (AZW3) format data within the same file, for backwards compatibility with older devices that only support MOBI.
How MOBI Files Function
MOBI files are designed to facilitate reflowable content, which means text display adapts to fit various screen sizes and resolutions. This is achieved using XHTML. Another key characteristic of this file type is the use of DRM (Digital Rights Management) to prevent unauthorized copying and distribution of copyrighted material.
A variety of software is used to access MOBI files, the most prominent being Amazon's Kindle app and Kindle e-readers. However, other reading platforms like Calibre, a free and open-source e-book library management application, also support the MOBI format. Reading applications such as Mobi File Reader, FBReader, and Stanza can open MOBI files on multiple devices including computers, tablets, and smartphones.
Alternatives to MOBI
The evolution of e-books has led to the development of alternative file formats that offer different features. The EPUB format, for instance, is widely supported across various e-readers except for the Kindle, and is known for its flexibility and compatibility. PDF is another universal format, though it is not reflowable like MOBI and EPUB. Amazon's newer KF8 (AZW3) format has also superseded MOBI on Kindle devices, providing better support for modern CSS3 and HTML5 features.