MOBI is the ebook format used by MobiPocket Reader, which bears the extension .mobi or .prc. The .prc extension is rarely used and is a vestige of MobiPocket Reader’s presence on the PalmOS (as PalmOS only supported the file extensions .prc and .db). In addition to the actual document contents, the .mobi format includes flags for a wide variety of information like the total length of the document, where in the document the reader left off, and so on.
MobiPocket was purchased by Amazon in 2005; Amazon’s propriety ebook format AZW is simply the MOBI format with a new DRM scheme incorporated into it.
- By Jason Fitzpatrick on 04/18/13