Such files may be stored as protected or unprotected files. PRC files are exactly digital books saved in the Mobi format, a format used for Mobipocket Reader. This software features modified press reviews using a Web companion, provision of the writer, biography for every ebook, comes with a virtual library wherein all formerly downloaded content may be viewed and accessed, a protected reading system as a result of the encryption of eBooks. PRC extension are data files generated for Mobipocket Ebook Reader.

The Mobipocket software package is free and composed of a variety of publishing and reading tools for PDA, Smartphones, cellular phones and e-book devices such as Symbian, Windows Mobile, Palm OS, webOS, Java ME, BlackBerry, Psion, Kindle and iLiad. Mobipocket Reader software is an E-Book reader for some Personal Digital Assistant (PDA), mobile phones and desktop operating systems. The Calibre and Geometer Plus FBReader software can be used in Mac OS, Linux and Microsoft Windows based systems to access and view MOBI files. The Mobipocket eBook format was already discontinued in January 2012. This reader in a full screen mode includes electronic bookmarks, full text search ability, and built in dictionary. These reflowable files can be read by using the Mobipocket Reader installed in the PDA which allows readers to put highlights, bookmarks, corrections, notes and drawings in any part of the book. PRC files are specifically used by PalmOS system or Palm Pilot PDA devices. MOBI files may also have a PRC file extension and may either be DRM protected or non DRM format. These MOBI files are generally classified as data files that contain digital e-book based on the Open eBook standard in XHTML format inclusive of JavaScript, text, images, and frames. The Mobipocket eBook is stored in the MOBI format and is affixed with MOBI file extension and is used by Mobipocket.

Mobi file reader browser