There are so many different ebook formats in existence that trying to get your ebook into every possible format isn’t practical. However it is a good idea to make your ebook available in the most popular ebook formats.
But first a little history.
Ebooks have already been around for a while. In the early days of ebooks people tried various ways of packaging ebooks, even including bundling text files into an EXE file. These “ebooks” typically ran on an application that looked like an internet browser and readers could click on buttons to navigate forwards and backwards through the book.
The problem is that downloading EXE files poses a fairly serious security risk to computers and this format quickly lost popularity as people became more aware of the risks of EXE files and computer viruses. It was only a matter of time until better formats were developed.
The four principal formats for ebooks now are:
- Portable Document Format (PDF)
- Kindle Format (AZW, KF8)
- Mobipocket Format (MOBI, PRC)
- Epub Format (EPUB)
- iBooks Format (iBook)
Now let’s look briefly at each of these formats. Then I’ll give you a table that shows at a glance how these formats correlate to the most popular ebook reading devices.
Portable Document Format (PDF)
In 1993 Adobe Systems created the Portable Document Format (PDF) as a standard format for document exchange. When a document was converted to PDF each page was basically an image of the original document. Since almost all computing devices have the capability to read PDFs, the PDF format has been widely adopted and remains one of the preferred methods of providing documents on the Internet today.
However, a problem arose with PDFs. With improvements in technology we started carrying around smaller and smaller devices. First it was laptops and then even smaller devices including Palm Pilots, Blackberries, and mobile phones.
The early versions of PDF were designed for computer screens and were not very suitable for viewing on smaller screens. Because each page was like an image the text couldn’t be “re-flowed” to fit on tiny screens. Readers became frustrated by the need to scroll horizontally as well as vertically to read a single page in a document.
Several new formats for ebooks have been developed which don’t have this problem. The most popular of these follow here.
Amazon’s Kindle Formats (AZW, KF8)
The Kindle format used by earlier Kindles is Amazon’s proprietary ebook format and based on the Mobipocket format (see below) with a different serial number scheme. Amazon purchased Mobipocket in 2005. These earlier Kindle books have the extension .azw
In late 2011, Amazon introduced Kindle Format 8. “KF8 is the next generation file format for Kindle books – replacing Mobi 7. As showcased on Kindle Fire, KF8 enables publishers to create great-looking books in categories that require rich formatting and design such as children’s picture books, comics & graphic novels, technical & engineering books and cookbooks.”
All books sold in the Kindle Store are currently delivered in a format which comprises versions for the older mobi format and Kindle Format 8.
The main extension for Kindle books is now .azw3
Mobipocket (MOBI, PRC)
The Mobipocket ebook format uses XHTML and is based on something known as the Open Ebook standard.
Mobipocket books can be read on the Amazon Kindle and on several other devices that support this format. They can also be read on devices running Mobipocket Reader, a free application from Mobipocket.
Mobipocket files have the extensions .mobi and .prc
The Mobi format is still particularly useful whenever you need to convert a document from some other format into a format that can be read on the Kindle.
Epub Format (EPUB)
The name ePub comes from “electronic publication”. Epub is a free and open standard for formatting ebooks and became an official standard of the International Digital Publishing Forum in September 2007, superseding the Open Ebook standard.
Epub is the format currently used by the majority of ebook stores, with the exception of Amazon Kindle Store, and including Barnes & Noble Nook Books, Apple iBookstore and Sony Reader Store.
Epub files have the extension .epub
Ebooks in the ePub format can be read on most ebook readers including the Barnes & Noble Nook, Kobo Reader, Sony Reader, Apple iOS and Android devices.
Kindle users cannot currently read ebooks in the ePub format on their Kindles. If a reader with an ePub ebook wants to read it on their Kindle they need to use 3rd-party software to convert the ebook from ePub format to mobi format which the Kindle can read.
IBooks Format (IBA)
This is Apple’s proprietary format based upon the ePub format, introduced in January 2012 with iBooks version 2.0.
Those are the major ebook formats. There are some others but they tend to be associated with earlier devices and are not as popular as those above. PDF technology, incidentally, has advanced considerably and now some PDF documents can also be re-flowed to fit on smaller screens.
The following table summarizes the major reading devices, ebook formats and where to buy them.