As the eBook market has grown and adapted to the changes in technology, we have seen a variety of eBook formats crop up. Some of these formats have now disappeared, some have grown strong with development and support, and some have hung on despite all efforts to get rid of them. Let's take a look at the most commonly recognized of these formats.
Overview: Mobipocket is a French company that started out in the days when Palm Pilots and other PDAs ruled. The company developed its eBook creation and reading software when eBooks were still in their infancy, and managed to flourish in the nascent market, eventually being purchased by Amazon in 2005. When Amazon decided to develop the Kindle, it was a logical step for the company to use its own proprietary format for the new device's eBooks.
The Mobipocket format is based loosely on HTML 3.2 and includes some unique formatting requirements. In the last 8 years, development on the display engine and HTML support has been pretty much non-existent, but the number of users who are familiar with the format is growing, especially with the Kindle becoming so popular.
DRM: The Mobipocket format allows books to be locked with Digital Rights Management (DRM) or not. When an encrypted file is downloaded from a retailer it is locked to the user's registered device. The Kindle uses the same DRM as the old Mobipocket format.
Devices: Kindle eBooks can be read on any of the Kindle devices, as well as in any of the Kindle Apps for PC, Mac, iOS, Android, Blackberry, etc.
Extensions: Mobipocket/Kindle files come in three different file extensions: .mobi, .prc, and .azw. There are no functional differences between these formats, and the files themselves are exactly the same.
Note: Joshua has written the most authoritative book on formatting books for the Kindle. Check out our Kindle Formatting website for more information.
Overview: The ePub format was developed as an industry-wide standard for eBooks. It is based on a variety of other technologies and standards, like Open eBook and XHTML 1.1, but its uniqueness is in how it combines these standards to provide a solid formatting foundation for eBooks of just about every shape and size. The display engines for ePub books have not quite caught up with the formatting standards, but already the formatting possibilities in ePub books have surpassed all of the other formats.
The ePub standard is maintained by the International Digital Publishing Forum (IDPF), a non-profit organization made up of technology and publishing companies. eBook Architects is an active member in the IDPF.
DRM: The most popular DRM option for ePub files is Adobe Content Server, which is utilized by Sony, Barnes & Noble, and many other eBook stores. Apple's iBooks application (on the iPad) utilizes Apple's own Fairplay DRM, which is not compatible with any other eBook device or application.
Devices: ePub books can be read on Windows and Mac computers with Adobe Digital Editions; on the Barnes & Noble NOOK and NOOKcolor; on all of the Sony Reader devices; on the iPad/iPhone/iPod Touch in iBooks and in other apps; on the Android system in Aldiko and other apps; and on Linux computers and other handheld devices using software like FBreader. They can also be read online in Bookworm and in Ibis Reader, a very good web-based reading system that can be accessed by mobile phones and computers, and is designed to be used quite effectively on the iPhone and Android devices.
Overview: Like Mobipocket, the eReader format also started in the early days of eBooks. However, unlike Mobipocket and most of the other formats, eReader/PDB is not based on HTML. It is based on a very basic text system called the Palm Markup Language (PML). A PML file is essentially a text file with markers added to create formatting. It can be converted into an actual eReader/PDB eBook file using one of the programs offered by eReader: Dropbook or eBook Studio.
DRM: eReader files can be locked down with native DRM.
Devices: eReader/PDB files are usually read in the eReader application, which is available for the iPhone and iPod Touch, Blackberry, Palm OS, PocketPC, Symbian, Windows, and Mac. Unencrypted eReader files can also be converted by other applications like Stanza and calibre into formats that are readable elsewhere.
Overview: The LIT format is based on Microsoft's Compressed HTML format, and can only be created using an add-on that only works in Microsoft Word 2003 or earlier. The format is not sold at most eBook stores, mostly because Microsoft has stopped supporting it. Despite that fact, there are still readers who are holding onto the LIT format.
DRM: LIT files can be encrypted with DRM. However, the LIT DRM encryption is notoriously easy to crack.
Devices: LIT files can only be read on Windows computers and Windows Mobile devices using the Microsoft Reader program. Unencrypted LIT files can also be converted by other applications like Stanza and calibre into formats that are readable elsewhere.
Overview: Smashwords is not a distinct eBook format, per se, but it needs to be included in this list. The Smashwords website allows authors and publishers to upload a Word document that is then automatically run through the "Meatgrinder" to be converted into 10 eBook formats. The Meatgrinder is somewhat particular about how the Word file is formatted, so it is always best to give it a file that has already been cleaned up and formatted with the Meatgrinder in mind and according to the Smashwords Style Guide.
Smashwords does not have the ability to overwrite the individual eBook files created by the Meatgrinder.
Note: Smashwords has some specific requirements for its eBooks, including changes to the copyright page, the addition of a license statement, and a separate ISBN. Without these and other issues addressed, an eBook will not be accepted into the Premium Catalog and cannot be distributed to other retailers like Sony and Barnes & Noble. Details can be found in the Style Guide.
DRM: Smashwords files are all DRM-free.
Overview: PDF files are common everywhere. There are a variety of programs that can create PDFs, including programs that install on your computer like a printer, allowing you to "print" a PDF file from just about any application. The main problem PDF files have in the modern eBook world is that the text in some PDF files cannot reflow to fit small screens. eBook devices like the Kindle and the Sony Reader, as well as devices like the iPhone, all have screens that are much smaller than a typical computer screen. As a result, when a PDF file is loaded on such a small device it usually needs to be zoomed in to be readable, usually forcing the user to scroll left and right to be able to read all of the text on a line.
Because PDF files are so common, they are distributed and sold by a variety of companies. It is important that any PDF you sell in the eBook market have the same active Table of Contents and Index as your other eBook files. Linking the TOC by hand is not difficult, but linking an index can be very time-consuming. Many times it is preferable to create a new PDF based on the eBook files being created, which can give you both re-flowing capabilities and full internal linking.
Devices: PDF files can be read on most computer systems with Adobe Acrobat Reader or 3rd party programs like FoxIt Reader. They are also supported in Adobe Digital Editions, a free eBook library and reading program available for Windows and Mac machines. The Kindle DX and Sony's devices also support PDF files natively (without the need to convert the file), though the DX's larger screen and automatic rotation give a better reading experience.
Overview: BBeB (BroadBand eBook) is a proprietary eBook format developed by Sony for use in the Sony Reader. The BBeB format is not open to the development community at large and can't be used on any other devices, so its scope is limited. On August 13, 2009, Sony announced that it would be converting its reader and retail systems to support ePub in place of the BBeB format, so BBeB is on its way out.
DRM: BBeB books can have one of three file extensions: LRF (binary book file, no DRM), LRX (binary book file, with DRM), and LRS (source XML file)
As you look at eBook sites you may occasionally find other eBook formats like RocketBook (RB), Hiebook (KML), PalmDOC/iSolo (PDB), and HaaliReader (FB2). These formats are essentially defunct and useless. The files can sometimes be converted by programs like calibre into more useful formats like ePub and Mobi to be read on newer devices.
Surprisingly, this list only shows a small number of the eBook formats out there. There are a variety of formats I have not mentioned because they are proprietary or software-specific, or because they are just not really used. As David Rothman at Teleread says, the amount of "eBabel" in the market makes it hard for consumers to navigate and make informed decisions. If you are an author or publisher who is looking for eBook solutions, the first six formats on this list (Mobipocket, ePub, Smashwords, eReader, LIT, and PDF) are the best ones to start off with. We can format eBooks in all of those formats for you. See our services page for more details.
If you have questions about these or other formats, please contact us.