E-Book Readers | UA - User Agents

Standards Based Development

A writer or publisher has many options when it comes to choosing a format for publication, including different e-book formats, that are used to create and publish e-books. While the average end-user might arguably simply want to read books, every format has its proponents. The myriad e-book formats are sometimes collectively referred to as the "Tower of eBabel". Nonetheless, some eBook formats are demonstrably more popular and more widely supported than others. The EPUB format is the most widely supported vendor-independent XML-based (as opposed to PDF) e-book format; that is, it is supported by the largest number of e-Readers. The popularity of Amazon.com's Kindle devices in America has led also to the prominence of KF8 and AZW formats; Kindle does not support EPUB.

The file size for texts without images depends on the file format, but is always relatively small compared with a richly illustrated text.

Format descriptions

Formats available include, but are by no means limited to:

NameFormatPublished asDefinition
Archos DiffusionArchos Reader.aeh

The AEH format is an XML-based proprietary format developed by the French firm Archos Diffusion. AEH files use a proprietary DRM and encryption method and are readable only in the Archos Player. It supports various input formats for text, audio or video, such as PDF, WMA, MP3, WMV, and allows multiple interactive functions such as bookmarking, advanced plain-text searching, dynamic text highlighting, etc.

Broadband eBooks (BBeB)Sony media.lrf; .lrx

The digital book format originally used by Sony Corporation. It is a proprietary format, but some reader software for general-purpose computers, particularly under Linux (for example, calibre's internal viewer, have the capability to read it. The LRX file extension represents a DRM encrypted eBook. More recently, Sony has converted its books from BBeB to EPUB and is now issuing new titles in EPUB.

Comic Book Archive filecompressed images.cbr (RAR); .cbz (ZIP); .cb7 (7z); .cbt (TAR); .cba (ACE)
Compiled HTMLMicrosoft Compiled HTML Help.chm

CHM format is a proprietary format based on HTML. Multiple pages and embedded graphics are distributed along with proprietary metadata as a single compressed file. In contrast, in HTML, a site consists of multiple HTML files and associated image files in standardized formats.


The Digital Accessible Information SYstem (DAISY) is an XML-based open standard maintained by the DAISY Consortium for people with print disabilities. DAISY has wide international support with features for multimedia, navigation and synchronization. A subset of the DAISY format has been adopted by law in the United States as the National Instructional Material Accessibility Standard (NIMAS), and K-12 textbooks and instructional materials are now required to be provided to students with disabilities.

DAISY is already aligned with the EPUB open standard, and is expected to fully converge with its forthcoming EPUB3 revision.


DjVu is a format specialized for storing scanned documents. It includes advanced compressors optimized for low-color images, such as text documents. Individual files may contain one or more pages. DjVu files cannot be re-flowed.

The contained page images are divided in separate layers (such as multi-color, low-resolution, background layer using lossy compression, and few-colors, high-resolution, tightly compressed foreground layer), each compressed in the best available method. The format is designed to decompress very quickly, even faster than vector-based formats.

The advantage of DjVu is that it is possible to take a high-resolution scan (300-400 DPI), good enough for both on-screen reading and printing, and store it very efficiently. Several dozens of 300 DPI black-and-white scans can be stored in less than a megabyte.


The .epub or OEBPS format is an open standard for e-books created by the International Digital Publishing Forum (IDPF). It combines three IDPF open standards:

  • Open Publication Structure (OPS) 2.0, which describes the content markup (either XHTML or Daisy DTBook)
  • Open Packaging Format (OPF) 2.0, which describes the structure of an .epub in XML
  • OEBPS Container Format (OCF) 1.0, which bundles files together (as a renamed ZIP file)

The EPUB format has gained some popularity as a vendor-independent XML-based e-book format. The format can be read by the Kobo eReader, Blackberry Playbook, Apple's iBooks app running on >iOS devices such as the iPhone, iPod Touch and iPad, Barnes and Noble Nook, Sony Reader, BeBook, Bookeen Cybook Gen3 (with firmware v. 2 and up), COOL-ER, Adobe Digital Editions, Lexcycle Stanza, BookGlutton, AZARDI, FBReader, Aldiko, Moon+ Reader and WordPlayer on Android, the Mozilla Firefox add-on EPUBReader, and Okular. Several other desktop reader software programs are currently implementing support for the format, such as dotReader, Mobipocket, uBook.

The only notable device lacking support for the EPUB format is the Amazon Kindle. There are a number of programs that can convert EPUB to formats the Kindle can read, including Calibre.

Adobe Digital Editions uses .epub format for its e-books, with drm protection provided through their proprietary ADEPT mechanism. The recently developed ADEPT framework and scripts have been reverse-engineered to circumvent this DRM system.

eReader (Formerly Palm Digital Media/Peanut Press)Palm Media.pdb

eReader is a freeware program for viewing Palm Digital Media electronic books which use the pdb format used by many Palm applications. Versions are available for iPhone, PalmOS (not webOS), Android, Symbian, BlackBerry, Windows Mobile Pocket PC/Smartphone, desktop Windows, and Macintosh. The reader shows text one page at a time, as paper books do. eReader supports embedded hyperlinks and images. Additionally, the Stanza application for the iPhone and iPod Touch can read both encrypted and unencrypted eReader files.

The program supports features like bookmarks and footnotes, enabling the user to mark any page with a bookmark, and any part of the text with a footnote-like commentary. Footnotes can later be exported as a Memo document.

On July 20, 2009, Barnes & Noble made an announcement implying that eReader would be the company's preferred format to deliver e-books. Exactly three months later, in a press release by Adobe, it was revealed Barnes & Noble would be joining forces with the software company to standardize the open EPUB and PDF eBook formats. Barnes & Noble e-books are now sold mostly in EPUB format.

FictionBook (Fb2)FictionBook.fb2

FictionBook is a popular xml-based e-book format, supported by free readers such as FBReader, Okular, CoolReader, Bebook and STDU Viewer.

The FictionBook format does not specify the appearance of a document; instead, it describes its structure and semantics. All the ebook metadata, such as the author name, title, and publisher, is also present in the ebook file. Hence the format is convenient for automatic processing, indexing, and ebook collection management. This also is convenient to store books in it for later automatic conversion into other formats.

Founder ElectronicsApabi Reader.xeb; .ceb

APABI is a format devised by Founder Electronics. It is a popular format for Chinese e-books. It can be read using the Apabi Reader software, and produced using Apabi Publisher. Both .xeb and .ceb files are encoded binary files. The Iliad e-book device includes an Apabi 'viewer'.

Hypertext Markup LanguageHypertext.htm; .html

html is the markup language used for most web pages. E-books using HTML can be read using a Web browser. The specifications for the format are available without charge from the W3C.

HTML adds specially marked meta-elements to otherwise plain text encoded using character sets like ASCII or UTF-8. As such, suitably formatted files can be, and sometimes are, generated by hand using a plain text editor or programmer's editor. Many HTML generator applications exist to ease this process and often require less intricate knowledge of the format details involved.

HTML on its own is not a particularly efficient format to store information in, requiring more storage space for a given work than many other formats. However, several e-Book formats including the Amazon Kindle, Open eBook, Compiled HTML, Mobipocket and EPUB store each book chapter in HTML format, then use ZIP compression to compress the HTML data, images, metadata and style sheets into a single, significantly smaller, file.

HTML files encompass a wide range of standards and displaying HTML files correctly can be complicated. Additionally many of the features supported, such as forms, are not relevant to e-books.

iBook (Apple) iBook.ibooks

The .ibooks format is created with the free iBooks Author ebook layout software from Apple Inc.. This proprietary format is based on the EPUB standard, with some differences in the CSS tags used in an ibooks format file, thus making it incompatible with the EPUB open standard. The End-User Licensing Agreement (EULA) that comes with iBooks Author states that "If you want to charge a fee for a work that includes files in the .ibooks format generated using iBooks Author, you may only sell or distribute such work through Apple". The "through Apple" will typically be in the Apple iBooks store. The EULA further states that "This restriction does not apply to the content of such works when distributed in a form that does not include files in the .ibooks format." Therefore, Apple has not included distribution restrictions in the iBooks Author EULA for ibooks format ebooks created in iBooks Author that are made available for free, and it does not prevent authors from repurposing the content in other ebook formats to be sold outside of the iBookstore. This software currently supports import and export functionally for three formats. ibook, Plain text and Adobe PDF. It does not support importing or exporting in EPUB format.

IEC 62448IEC 62448

IEC 62448 is an international standard created by International Electrotechnical Commission (IEC), Technical Committee 100, Technical Area 10 (Multimedia e-publishing and e-book).

The current version of IEC 62448 is an umbrella standard that contains as appendices two concrete formats, XMDF of Sharp and BBeB of Sony. However, BBeB has been discontinued by Sony and the version of XMDF that is in the specification is out of date. The IEC TA10 group is discussing the next steps, and has invited the IDPF organization which has standardized EPUB to be a liaison. It is possible that the current version of EPUB and/or the forthcoming EPUB3 revision may be added to IEC 62448. Meanwhile a number of Japanese companies have proposed that IEC standardize a proposed new Japanese-centric file format that is expected to unify DotBook of Voyager Japan and XMDF of Sharp. This new format has not been publicly disclosed as of November, 2010 but it is supposed to cover basic representations for the Japanese language. Technically speaking, this revision is supposed to provide a Japanese minimum set, a Japanese extension set, and a stylesheet language. These issues were discussed in the TC100 meeting held in October 2010 but no decisions were taken besides offering the liaison status to IDPF.

KF8 (Amazon Kindle)Kindle.azw; .kf8

With the release of the Kindle Fire reader in late 2011, Amazon.com also released Kindle Format 8, their new file format. The .kf8 file format supports a subset of HTML5 and CSS3 features, with some additional nonstandard features; the new data is stored within a container which can also be used to store a MOBI content document (allowing limited backwards compatibility).

Older Kindle eBook readers use the proprietary format, AZW. It is based on the Mobipocket standard, with a slightly different serial number scheme (it uses an asterisk instead of a dollar sign) and its own DRM formatting. Because the eBooks bought on the Kindle are delivered over its wireless system called Whispernet, the user does not see the AZW files during the download process. The Kindle format is now available on a variety of platforms, such as through the Kindle app for the iPad.

Microsoft LITMicrosoft Reader.lit

DRM-protected LIT files are only readable in the proprietary Microsoft Reader program, as the .LIT format, otherwise similar to Microsoft's CHM format, includes Digital Rights Management features. Other third party readers, such as Lexcycle Stanza, can read unprotected LIT files.

The Microsoft Reader uses patented ClearType display technology. In Reader navigation works with a keyboard, mouse, stylus, or through electronic bookmarks. The Catalog Library records reader books in a personalized "home page", and books are displayed with ClearType to improve readability. A user can add annotations and notes to any page, create large-print e-books with a single command, or create free-form drawings on the reader pages. A built-in dictionary allows the user to look up words.

Microsoft announced that Microsoft Reader has been discontinued from August 30, 2012.

Mobipocket Mobipocket.prc; .mobi

The Mobipocket e-book format is based on the Open eBook standard using XHTML and can include JavaScript and frames. It also supports native SQL queries to be used with embedded databases. There is a corresponding e-book reader.

The Mobipocket Reader has a home page library. Readers can add blank pages in any part of a book and add free-hand drawings. Annotations — highlights, bookmarks, corrections, notes, and drawings — can be applied, organized, and recalled from a single location. Images are converted to GIF format and have a maximum size of 64K, sufficient for mobile phones with small screens, but rather restrictive for newer gadgets. >Mobipocket Reader has electronic bookmarks, and a built-in dictionary.

The reader has a full screen mode for reading and support for many PDAs, Communicators, and Smartphones. Mobipocket products support most Windows, Symbian, BlackBerry and Palm operating systems, but not the Android platform. Using WINE, the reader works under Linux or Mac OS X. Third-party applications like Okular and FBReader can also be used under Linux or Mac OS X, but they work only with unencrypted files.

The Amazon Kindle's AZW format is basically just the Mobipocket format with a slightly different serial number scheme (it uses an asterisk instead of a dollar sign), and .prc publications can be read directly on the Kindle. The Kindle AZW format also lacks some Mobipocket features such as JavaScript.

Amazon has developed an .epub to .mobi converter called KindleGen (supports IDPF 1.0 and IDPF 2.0 epub format, according to the company).

Multimedia eBooks Eveda.exe or .html

A multimedia ebook is media and book content that utilizes a combination of different book content formats. The term can be used as a noun (a medium with multiple content formats) or as an adjective describing a medium as having multiple content formats.

The 'multimedia ebook' term is used in contrast to media which only utilize traditional forms of printed or text books. Multimedia ebooks include a combination of text, audio, images, video, and/or interactive content formats. Much like how a traditional book can contain images to help the text tell a story, a multimedia ebook can contain other elements not formerly possible to help tell the story.

With the advent of more widespread tablet-like computers, such as the smartphone, some publishing houses are planning to make multimedia ebooks, such as Penguin.s

Newton eBookNewton eBook.pkg

Commonly known as an Apple Newton book; a single Newton package file can contain multiple books (for example, the three books of a trilogy might be packaged together). All systems running the Newton operating system (the most common include the Newton MessagePads, eMates, Siemens Secretary Stations, Motorola Marcos, Digital Ocean Seahorses and Tarpons) have built-in support for viewing Newton books. The Newton package format was released to the public by Newton, Inc. prior to that company's absorption into Apple Computer. The format is thus arguably open and various people have written readers for it (writing a Newton book converter has even been assigned as a university-level class project).

Newton books have no support for DRM or encryption. They do support internal links, potentially multiple tables of contents and indexes, embedded gray scale images, and even some scripting capability (for example, it's possible to make a book in which the reader can influence the outcome). Newton books utilize Unicode and are thus available in numerous languages. An individual Newton book may actually contain multiple views representing the same content in different ways (such as for different screen resolutions).

Open Electronic PackageOpen eBook.opf

OPF is an XML-based e-book format created by E-Book Systems; it has been superseded by the EPUB electronic publication standard.

Portable Document FormatAdobe Portable Document Format.pdf

A file format created by Adobe Systems, initially to provide a standard form for storing printable documents containing a set of page images. The format derives from PostScript, but without language features like loops, and with added support for features like compression, passwords and DRM. Because PDF documents can easily be viewed and printed by users on a variety of computer platforms, they are very common on the World Wide Web. The specification of the format is available without charge from Adobe.

Because the format is designed to reproduce page images, the text traditionally could not be re-flowed to fit the screen width or size. As a result, PDF files designed for printing on standard paper sizes were less easily viewed on screens with limited size or resolution, such as those found on mobile phones and e-book readers. Adobe has addressed this drawback by adding a re-flow facility to its Acrobat Reader software.

Many products support creating and reading PDF files, such as Adobe Acrobat, PDFCreator, OpenOffice.org, iText, ConTeXt and FOP, and several programming libraries. Third party viewers such as xpdf are also available. Mac OS X has built-in PDF support, both for creation as part of the printing system and for display using the built-in Preview application.

PDF files are supported by almost all modern e-book readers, tablets and smartphones. However, PDF re-flow being newer is not supported by all devices that can open PDF files. Android's Repligo PDF Reader and EzPDF stand out as products supporting PDF and proper re-flow technologies. Reflow is usually found under the "view" options, and is usually called "word-wrap". EzPDF also has an IOS version suitable for Apple devices.

Plain text filestext.txt

E-books in plain text exist. The size in bytes is simply the number of characters, including spaces, and with a new line counting for 1 or 2. For example, the Bible, which is approximately 800,000 words, is about 4 MB. The ASCII standard allows ASCII-only text files to be interchanged and readable on Unix, Macintosh, Microsoft Windows, DOS, and other systems. These differ in their preferred line ending convention and their interpretation of values outside the ASCII range (their character encoding). Conversion of files from one to another line-ending convention is easily possible with free software on most computers.


Plucker is an Open Source free mobile and desktop e-book reader application with its own associated file format and software to automatically generate Plucker files from text, PDF, HTML, or other document format files, web sites or RSS feeds. The format is public and well-documented. Free readers are available for all kinds of desktop computers and many PDAs.


PostScript is a page description language used in the electronic and desktop publishing areas for defining the contents and layout of a printed page, which can be used by a rendering program to assemble and create the actual output bitmap. Many office printers directly support interpreting PostScript and printing the result. As a result, the format also sees wide use in the Unix world.


The digital book format used by a popular digital library company 超星数字图书馆 in China. It is a proprietary raster image compression and binding format, with reading time OCR plug-in modules. The company scanned a huge number of Chinese books in the China National Library and this becomes the major stock of their service. The detailed format is not published. There are also some other commercial e-book formats used in Chinese digital libraries.


TEBR file format is designed with mobile devices, PDAs, and phones in mind, although a Windows Desktop version is also available. The first reader to support this format is the Tiny eBook Reader. It allows compression and encryption, but does not allow for conversion to other formats.

Text Encoding InitiativeTEI Lite.xml

TEI Lite is the most popular of the TEI-based (and thus XML-based or SGML-based) electronic text formats.

TomeRaiderTomeRaider.tr2; .tr3

E-Book-Reader Sprite

.ebookreader{background-image:url("http://dev.bowdenweb.com/ua/e-book-readers/i/sprite-ebook-formats.png"); background-repeat:no-repeat} .epub{width:14px; height:20px; background-position:3px -3px} E-Book-Readers Sprite E Book Reader File Formats Sprite

The most notable formats are:

Other mobile text viewers

Portable multimedia players and smartphones that include a text viewer, e.g. several Cowon players, including the Cowon D2 and the iAUDIO U3 and Mobipocket Reader for Symbian OS and Windows Mobile mobile phones and devices.

Adobe Reader mobile also turns Windows Mobile devices (for example, Samsung Omnia) into e-book viewers. Apple's iPad, iPhone, and iPod Touch are acquiring status as e-book readers through a variety of e-reader apps.

WordPlayer, FBReader, Aldiko or Mantano Reader turn Android phones into e-book readers. The BlackBerry PlayBook has a number of excellent e-book applications.

Palm OS based devices and smartphones are also usable for reading books.

PalmOS supports PalmDoc, iSilo, Mobipocket reader, PDF, HTML conversion, text format, Handstory, TealDoc among many other software titles, and word processing.

Some mobile devices support word processing. Some fully functional tablet notebooks (with screens that turn 180 degrees and lie with the back to the keyboard) and subnotebooks are used as e-book readers.

Amazon Kindle

The Amazon Kindle is a series of e-book readers that enable users to shop, download, browse, and read e-books, newspapers, magazines, blogs, and other digital media via wireless networking.

Most of the devices use an E Ink electronic paper display that is capable of rendering 16 shades of gray to simulate reading on paper while minimizing power consumption.

Amazon Kindle (First Generation)

The first Amazon Kindle was released on 2007-11-19 and sold out in five and a half hours, remaining out of stock for five months until late 2008-04. First Generation Amazon Kindle remains the only Kindle with expandalbe memory, via an sd card slot.

Amazon Kindle Touch

Kindle Touch became available on 2011-11-15 and features a touchscreen, as well as via 3g the Kindle Touch is able to connect to the Kindle Store, download books/periodicals, an access Wikipedia.

Kindle Touch

Kindle Fire is a mini tablet version of Amazon.com's Kindle e-book reader, released on 2011-11-15 with a 7-inch multi-touch display with ips technology and running on Android.

Kindle Fire includes access to the Amazon Appstore, streaming videa and Kindle's e-books.

Kindle Fire

Kindle Fire

Barnes & Noble Nook

E-book Reader E-book Reader E-book Reader E-book Reader E-book Reader E-book Reader

NOOK is a brand of e-book reader developed on Android by Barnes & Noble. The original Nook was released in 2009-10.

Barnes & Noble entered a partnership with Microsoft on 2012-04-30 to spin off its Nook and college businesses into a subsidiary.

Barnes & Noble NOOK

Nook 1st Edition

The Nook 1st Edition included both Wi-Fi and at&t 3g wireless connectivity, a six-inch E ink display, as well as a separate, smaller color touchscreen that serves as the primary input device.

Barnes & Noble Nook 1st Edition

Nook Simple Touch

Nook Simple Touch (also called the Nook Touch) is the second generation of the Nook e-book reader. Nook Simple Touch features an 800x600 E Ink screen with a touchscreen that uses a network of infrared beams slightly above the surface of the screen, as well as wireless connectivity via Wi-Fi 802.11 b/g/n, and has a usb port to charge/connect with a computer.

Nook Simple Touch

Nook Color

Nook Color is a color version of the Nook e-reader and features a 7-inch (18cm) tablet with full-color multitouch touchscreen input.

Nook Color became available on 2010-11-16.

Nook Color

Nook Tablet

Nook Tablet is a tablet that follows the Nook Color and is intended to compete with both e-book readers and tablets.

Nook Tablet was released on 2011-11-17.

Nook Tablet, NOOK Tablet

Kobo eReader

E-book Reader

The Kobo eReader is an e-book reader marketed as a minimalist alternative to its more expensive competition. Like most e-book readers, Kobo uses an electronic ink screen.

Kobo eReader

Sony Reader

E-book Reader E-book Reader E-book Reader E-book Reader

The Sony Reader is an e-book reader that is viewable in direct sunlight, requires no power to maintain a static image, and is usable in both portrait and landscape orientations.

Sony Reader e-books are sold via the Sony eBook Library Store.

Sony Reader can display pdfs, epubs, rss Feeds. jpgs, Sony's proprietary bbeb format, as well as play mp3 and unencrypted aac audio files.

Note: as of 2010-07, the Sony eBook Store no longer is using the bbeb format, and have converted all books to epub format.

The Sony Reader Story is the Sony Reader's marketplace, as well as offering the Sony Reader and Reader Applications.

Sony Reader


E-book Reader E-book Reader

The iPad is a line of tablets developed by Apple, primarily as a platform for audio-visual media. iPad runs on iOS and can run its own applications, as well as iPhone applications. Without modification(s), or a developer certificate, iPad will only run programs approved by Apple and distributed via the Apple App Store, with the exception of programs that run inside the iPad's web browser.

iPad is controlled by a multitouch display, which is different from most previous tablets that generally relied on a pressure-triggered stylus. iPad is also controlled by a virtual onscreen keyboard.

Adobe® Digital Edition

Adobe® Digital Edition software offers an engaging way to view and manage eBooks and other digital publications. Use it to download and purchase digital content, which can be read both online and offline. Transfer copy-protected eBooks from your personal computer to other computers or devices. Organize your eBooks into a custom library and annotate pages. Digital Editions also supports industry-standard eBook formats, including PDF/A and EPUB.

Sample eBook Library - Adobe Digital Editions

References and Resources