eBook Format File Extentions

This section attempts to define and identify all (or most) of the eBooks formats. With the great proliferation of formats a new user can easily become confused. The most important ones are always the ones that work on the device or devices you own but if you have a choice the most important ones are the ones that have the most eBook dealers or most eBooks available. Today these formats include AZW Amazon, MOBI MobiPocket, LIT Microsoft, PNPd Palm eReader, and BBeB Sony. Another very popular format is PDF from Adobe, however it does not tend to work as well on portable mobile devices due to the screen size. It is more suited to computers since it often expects full paper size pages. A new emerging eBook standard format is ePUB. Some of the formats in the list below are only available for a few or even one type of device. Some are more standardized. Be sure your device will read the format you choose.

ABW - File format used by AbiWord. If compressed it is ZABW.
ACSM - File format used to provide DRM on Adobe eBooks PDF and ePUB.
AEH - File format used by eBooksWriter.
AZW - The Amazon proprietary format. This is very close to the MOBI format sometimes with and sometimes without DRM. The DRM is unique to the Amazon Kindle.
AZW1 - The Amazon proprietary format. It is the TPZ format always with a custom DRM.
BBeB - The Sony proprietary format. Stands for Broadband EBook, also known as LRF because of the file extension.
CBR/CBZ - Compressed container for images. The R means it is RAR compressed while Z means it is zipped compressed. The internal format can be any of several image formats and CBR/CBZ readers display these as multiple pages of a book. The name means Comic Book Reader but the use is for any book where the content contains basically pictures.
CHM - Compressed HTML, often used for Windows help files. It has become very popular for distribution of texts and other support materials over the Web.
DJVU - format by Lizardtech that is more and more widely used for scientific publications. Its main characteristics is that the compress ratio is about 10x better than in .pdf format at the same quality. Nothing beats it at the moment for b&w text and pictures.
DNL - A digtital webbook format used by Desktop Author.
DOC - This format could be a document in Microsoft Word format, which uses a .doc extension, or in PalmDOC
DOCX - This is the latest Office Open XML format used in Word 2007 and later. Older versions of Word can be upgraded to support this format.
EBA - proprietary eBook format. Specifically supported by eBook Readers for the Chinese language.
EBAML same as EBA 2.0 - Used on the Dr. Yi Reader and other China products
ePUB standard. An open format defined by the Open eBook Forum of the International Digital Publishing Forum (). It is based on XHTML and XML. It is an evolving standard. Current specifications are found at the idpf web site. Adobe has DRM for this format.
-ER.PDB - A Palm database format for the eReader reader. The ER is used to distinguish this format.
EXE format means that the eBook is actually a PC executable. Basically the eBook includes the program to display it.
FB2 - FictionBook format, based on XML and viewable by various e-book software solutions for Windows, Linux, PocketPC and Palm OS. Used by the HaaliReader, FBReader and the PalmFiction.
FUB - Franklin eBook format.
GPF - Ganaxa Publishing Format, allowing hot spots and embedded rich media content.
GPX - A protected Ganaxa document.
HTML - Hyper Text Markup Language is the backbone of the World Wide Web. Many texts are distributed in this format. In addition, some eBook readers support Cascading Style Sheets (CSS) that are basically a master style guide for HTML pages.
HTXT seems to be encrypted TXT files that are DRM locked to a particular reader. They are unique to Hanvon devices. An earlier version was called MTXT.
IMP - an eBook format used by eBook Technologies ETI-1 (REB 1200/Softbook Reader) or ETI-2 (EBookwise-1150/Gemstar 1150). Some programs convert to it. It is considered a terminal format but see: IMP software.
-IS.PDB - A Palm database format for the ISilo reader. The IS is used to distinguish this format.
KML - HieBook eBook format.
LIT - Microsoft's native format for its Microsoft Reader
LRF - also: BBeB book. Sony's proprietary format. Supported by the Sony Librie and Sony Reader
LRS - also: BBeB Xylog XML. Source format for BBeB books, which is compiled into LRF for reading on the device
LRX - A protected BBeB document. The Sony Librie and Sony Reader use mutually incompatible formats
MOBI - MobiPocket format, usable with MobiPocket's own reading software on almost any PDA and Smartphones. Mobipocket's Windows PC software can convert .chm, .doc, .html, .ocf, .pdf, .rtf, and .txt files to this format
NP - format is the Newspaper download format used by NewspaperDirect for their PressDisplay product.
OEB - Open eBook format. an ebook format used by EBookwise-1150, MobiPocket, and Microsoft Reader. This standard is an older version of ePUB
ODT - This is an open standard, document format used in OpenOffice.org, Star Office and many other word processors.
OSIS - This is an XML Schema definition for Bibles and other Biblical research texts.
PDB - Palm Database File. Can hold several different e-book formats targeting Palm-enabled devices, commonly used for PalmDOC (AportisDoc) e-books and eReader formats as well and many others.
PDF - Portable Document Format created by Adobe for their Acrobat products. It is the defacto standard for document interchange. Software support exists for almost every computer platform and handheld device. Some devices have problems with PDF since most content available is scaled for either A4 or letter format, both of which are not easily readable when reduced to fit on small screens. Some Readers can reflow some PDF documents, including the Sony PRS505, to accommodate the small screen. Some e-book readers, including the iRex iLiad, have a pan-and-zoom feature that aids readability, but extracts a price in ergonomics.
PKG a format used on the Apple Newton.
PNPd -€ format used by the eReader program. This is a popular format (Also known as PML).
PRC - Palm Resource File. Often holds a Mobipocket eBook but occasionally holds an eReader or AportisDoc eBook. Most often it is a Palm executable.
RB - Rocket eBook format made for the Rocket eBook device and the Gemstar RCA REB 1100.
RTF - Rich Text Format is a document interchange format available supported by some e-book readers, and also by many Word processing applications including MS Word and OpenOffice. It is the preferred format for many users who create their own content for the Sony Reader.
SGF - Native format for Sigil, a direct editor for ePUB.
STK - STAReBOOK's proprietary format
TCR - eBook for EPOC
TeBR - Tiny Ebook Reader format also used by Fictionwise.
TPZ - Topaz file extension used on Amazon Kindle
TXT - Text is the base type, with no formatting applied other than space, paragraph, end of line, new line, and tab. It is usable in many e-book devices.
TR - Tome Raider file. Tome Raider is an eBook format that features support for very large books such as reference books, encyclopedias, and dictionaries. Their latest format is called TR3.
VBK - eBook format from VitalSource that features graphics support.
XDXF - Dictionary exchange format based on XML.
XEB - format used by Apbi eBooks in Chinese primarily.
XHTML - specialized version of HTML designed to conform to XML rules of construction. It is the standard format for epub data.
XML - general purpose markup language for exchange of data. In the context of eBooks it is generally confined to XHTML and RSS feeds although some other formats have been defined.
WOLF - Proprietary format used by HanLin eBook in their V2B, V3, and V8 eBook readers. Usually a .wol extension is used. Also used by JCNIP on their Dr. Yi ebook reader.
zTXT - format used by the WeaselReader on Palm devices. Has a .pdb extension.
ZNO - proprietary format for Zinio electronic subscription magazines. These magazines include multimedia material like photos and videos. It is rumored that the format is based on DJVU.

A number of e-book readers and PDAs play music (usually in MP3) and display graphics (usually in JPG).
LRC - A annotation format originally intended for Lyrics. It can also be used for read along eBooks. It is a text file that can be synced with audio or video files with an appropriate program.