More people are reading eBooks than ever before. Their lower cost and more portable nature means they now account for 30 percent of all book sales in the United States.
But not all of it is good news for consumers.. Unlike MP3s, which you can throw into any music player and expect them to work, e-books are a maze of proprietary, open standard formats. To further complicate matters, not all e-readers support all formats.
In this article, we take a look at some of the most common formats, explain their pros and cons, and tell you which readers support them.
EPUB is the most widely adopted eBook file format. Initially developed by the International Digital Publishing Forum (now part of the World Wide Web Consortium), it replaced the old Open ebook (OEB) format in 2007.
Because EPUB is free to use, open standard, and vendor independent, it has become the most common eBook format. Although not often seen, it can even support color images, SVG graphics, interactive elements, and full-length videos.
In many ways, it's the ebook equivalent of your trusty MP3, in both good and bad ways. Almost all e-readers and computer operating systems support the format, but publishers can also include it in any DRM system of their choice (although you can remove the DRM on any e-book you have).
And the drawback? Amazon Kindle devices cannot read it (except Kindle Fire tablet). If you have a book in the EPUB format that you want to read on your Kindle, you can convert eBooks to a different format using Caliber. How to Convert eBooks to Kindle Format When Importing into Your Library How to Convert Ebooks to Kindle Format When Importing into Your Library Caliber has another nifty trick up its sleeve:it can automatically convert any eBook to Kindle MOBI format when you import it into your library . Read more.
Like EPUB, the MOBI format also grew out of the old OEB format. The French company Mobipocket forked it in 2000 and it became the basis of its Mobipocket Reader software.
Amazon bought the company in 2005 and allowed it to thrive for 11 years. In October 2016, Amazon finally shut down the Mobipocket website and servers, but the MOBI format lives on.
There are some key differences between EPUB and MOBI. More pertinently, it is not an open standard and therefore not publicly available. It also doesn't support sound or video.
Once again, it's endorsed by every major e-reader with one exception:the Barnes and Noble Nook.
Note: The MOBI format also uses the PRC extension.
The AZW and AZW3 extensions are Amazon's two proprietary eBook formats. AZW is the older of the two; it debuted alongside the first Kindle in 2007. AZW3 arrived in 2011 with the release of the Kindle Fire reader.
Every time you buy or download an Amazon eBook How to Download Free Amazon Kindle eBooks on Your PC How to Download Free Amazon Kindle eBooks to Your PC Even if you don't have a Kindle, you can still download free Kindle eBooks on PC . This article walks you through the process. Read More AZW3 is more advanced than AZW. Supports more styles, fonts, and layouts.
Behind the scenes, both formats are extremely similar to the MOBI format. Although it has never been publicly confirmed, it is generally assumed that the reason Amazon bought Mobipocket was so that it could use the underlying technology as the basis for its AZW format. Unlike MOBI, Amazon formats support video and sound.
Because AZW is proprietary, it is not as widely supported by e-readers as EPUB and MOBI. Naturally, all of Amazon's Kindle products can read the format, but other popular devices like Nook and Kobo e-readers can't.
Both Android and iOS can read AWZ, and it's also readable in popular eBook management apps like Caliber and Alpha.
The other common proprietary ebook format you're likely to stumble upon is IBA. This is the format used for books created in Apple's iBooks Author app.
Technically, the format is very similar to EPUB. However, it relies on custom widget code in the Apple Books app to work, and is therefore not universally readable on all e-readers.
Remember, this format is only used for books written in iBooks Author. If you buy the best-selling ebooks from the iTunes store, they will be delivered in EPUB format (although they will be restricted by DRM).
The iBook format supports video, sound, images, and interactive elements.
The last big e-book format in circulation is the PDF. Due to the widespread adoption of the format on the web, PDF files have become a popular way to deliver e-books.
Its big drawback is the lack of native reflux. Mirroring is the term used to describe when a file can adapt its presentation according to the screen size or settings a user has selected.
All dedicated eBook formats offer reflow based on the sequence of objects in the content stream. The PDF format can circumvent the lack of regular reflow by using tags to define the underlying structure of a document. However, tagged PDF files are not yet well supported by eBook readers.
On the plus side, it's only the second format on the list that is open standard; it became ISO 32000 in 2008.
There are some less common formats that you may see from time to time...
LRS, LRF, and LRX are the file extensions for the Broadband eBook Format. They were proprietary formats that Sony created for use in its own range of eBook readers.
LRS is now open standard, but LRF and LRX remain closed. In any case, Sony has abandoned all three formats in favor of EPUB.
XML-based FB2 started life in Russia. It is common among collectors of e-books thanks to its ability to store metadata within the e-book file itself.
It is also widely used as a storage format due to the ease with which it can be converted to other formats.
DJVU is popular in the scientific community. It has compression that is about 10 times better than PDF; You can store over 100 black and white scans in less than a megabyte.
Note: You can reduce the size of a PDF with a few compression tricks 4 ways to compress and reduce the size of a PDF file 4 ways to compress and reduce the size of a PDF file Are your PDF files too big to handle? You can often drastically reduce the size of your PDF documents. We show you how you can reduce and compress PDF files. Read more.
LIT was Microsoft's proprietary electronic book format. When DRM was enabled, books could only be read in the Microsoft Reader app.
In 2011, Microsoft discontinued the LIT format. The reader disappeared earlier this year.
The rich text format is compatible with all e-readers on the market. It has an advantage over TXT due to its ability to retain special characters and its support for reflow and text formatting.
Really, the only formats you need to worry about are EPUB, MOBI, and AZW.
If you plan to build a large ebook library on your computer that is compatible with most readers, stick with EPUB. If you want to create a library that is predominantly Kindle-specific, choose MOBI. It doesn't have as many features as AZW but more devices can read it.
For more information on file types, see our guide to image file types. JPEG, GIF, or PNG? Image file types explained and tested JPEG, GIF, or PNG? Image File Types Explained and Tested Do you know the differences between JPEG, GIF, PNG, and other image file types? Do you know when you should use one instead of the other? Fear not, MakeUseOf explains it all! Read More Video File Types Explained &Compared AVI, MKV or MP4? Video File Types Explained &Compared Why are there so many video formats? It's confusing! But don't worry, we are here to help you. Here you will find everything you need to know about video formats, containers and codecs. Read more.
