When it comes to ebooks it all about digital format, much like region settings for DVDs or — and here I’m dating myself — different old video cassette formats that only work in certain parts of the world. Ebooks come in different formats, and are actually available in a variety of different ones, but not every ebook can be available to readers in ten or twenty different formats.
Publishers and self-publishers have to put in the work at creating and converting ebooks to specific formats which costs time and money.
The good news is that the ereading world cottoned on to this fairly early and there are now essentially three main accepted formats of ebook: EPUB, MOBI and PDF.
With the explosion of the ereader market over the last couple of years, the EPUB format — named for the file extension .epub — has come out as the most prevalent and popular of the ebook formats. Epub employs what is known as reflowable content, which according to Wiki is:
“A type of electronic document that can adapt its presentation to the output device. Typical desktop publishing (DTP) output formats like PostScript or PDF are page-oriented, so are not generally reflowable (but see discussion below for PDF), whereas the world wide web standard, HTML is a reflowable format.”
What this means then is that when an ebook is made using the EPUB format it will adapt to the particular ereader’s or tablet’s display settings so that things like new chapters, page breaks and page numbers all look correctly organized and displayed. This is an important facet of ebooks, as many books have different layout styles with unusual breaks and spacing; the book House of Leaves by Mark Z. Danielewski comes to mind.
Because of this important and advantageous component, the EPUB format is accepted by most ereaders and ereading devices. The one exception is Amazon and its own proprietary ereading device and tablet, the Kindle.
The MOBI format is a specific ebook format developed by Amazon.
Much like Amazon wants to control everything in their effort at world domination, they want to control the ebook market as much as they possibly can. So they created their own specific line of ereaders and tablet readers known as the Kindle.
The key with the Kindle is that it uses the MOBI format of ebook, but does not accept or recognize the widely used EPUB format. What this means is that when you buy an ebook through Amazon, it will always be in the MOBI format and you will need to have a Kindle to read it.
There is an exception to this, however, which is if you have an iPad or a tablet device that uses apps, you can get the Kindle app for free, which will allow you to read MOBI format ebooks.
And yes, this includes cell phones too.
The final ebook format I want to talk about are PDFs.
PDF, or Portable Document Format, has been around for a long time. Adobe developed and released the format in 1993. PDFs have been used for many years as an easy way of making specific documents including text, photos, images and links easily mobile and emailed or saved.
The key to PDFs is that you set the display and layout and it remains that way once saved; in other words static.
Back in the early days of ebooks, PDF was the only real and viable format for the digital book.
I can remember buying and downloading Riding the Bullet by Stephen King, which was the first mass-market electronic book published back in 2000.
Most ereaders will accept the PDF format, and this includes the Kindle line also. So ebooks in the PDF format are very easy to use on just about any device, whether it’s your computer, your tablet, your ereader, or even your cell phone. The main problem with PDFs is as I said above, where it is a “fixed-layout flat document.” So when reading PDFs on an ereader if the page size is beyond the dimensions of the screen, it is necessary to zoom in or out to mess with how you want the text displayed on the screen. This can even result in an unsatisfactory display where you have to keep moving the page around to read the full text.
These three ebook formats are the most widely used with ebooks. They each have their own advantages and disadvantages. A few years ago it was a lot harder to decide which format to go with because they had their limitations, but with the development of apps this has greatly changed. Most ereaders now have their own apps, such as the Kobo, Kindle and Nook.
There is also the free program Adobe Digital Editions which allows you to read EPUB and PDF ebooks on your computer.
The question is whether one day there will be a single accepted format of ebook, like with Blu-Ray DVDs. If this does happen, at the moment it looks like it will be years in the future, as EPUB and MOBI continue to duke it out for the winning position, while PDF just wants everyone to get along.