Curious As To Why You Might Ever Want or Need an ePUB File? Read On!
How Can A MOBI File Be Anything Like A CAKE?
When we’re called by prospective clients, we’re asked a lot of questions. Some of them are about layout, some about functionality, and some are simply what seem to be practical questions, to the typical person or new eBook publisher.
One of the things that I’m often asked is “Why do I need an ePUB file? I only want to publish to the Amazon Kindle program, which uses MOBI, so why do I need to pay for an ePUB?”
What is an ePUB File? What's in a MOBI File?
As background, to address this, it helps to know that of all the major retailers, Amazon uses an eBook format called “MOBI,” and all the others (B&N, iBooks, KoboBooks, Sony, etc.) use the other major eBook format, “ePUB.” Basically, the eBook DNA of both formats is 98% identical; only at the very end of the process does the bookmaker make the decisions that end up creating an ePUB file versus a MOBI file, or vice-versa. So, by and large, it’s not twice as much for a company to give you both formats (and if anyone tells you that—find a different formatter!); it’s only a bit more money, as a large part of the work is the same.
The exception to this is what’s called “Fixed Layout” or “Fixed Format,” but that’s a topic for another day.
BUT: MOBI Kindle Files are not editable.
What most folks don’t know is that a MOBI Kindle file is not editable. When I tell people that, they naturally ask me, “but, if I want to make changes, how does that happen?” So, here’s the real deal on the basics between ePUB and MOBI:
A MOBI file is a finished, completed product. It is, essentially, like a Cake. When it’s finished, it’s great—but if you wanted to, you couldn’t take that cake apart and get your ingredients back. You couldn’t decide that you wanted to replace (say), half your white sugar with brown sugar. You can’t get your eggs, your flour, your sugar or flavorings back. It’s great, but it’s CAKE, not cake ingredients. If you decide to change your cake, you have to make a whole new cake, from new ingredients.
(If you want to get techy—a MOBI file is a binary database file that is built from its HTML source).
But, What If You Need To Change Your MOBI File?
But an ePUB file, on the other hand, isn’t just CAKE. It’s a cake that you can disassemble, if you need to. You can get your flour, your eggs, your sugar and your flavorings back from your ePUB. Your ePUB exists in two ways simultaneously; it’s both a finished book (cake!) and the ingredients. This is because an ePUB format isn’t like a MOBI format—it’s a bunch of files (ingredients) zipped into a unique format (ePUB). The “book” exists when it’s zipped into that special ePUB format. But if you know how, you can simply open up that formatted book, and you can add sugar, eggs, flour (text, formatting, other elements), make your changes, and zip those ingredients right back up into…a BOOK. It’s a bit like magic. You can wave your wand at an ePUB, and say “EPUB-liarmus!” and you can take it apart, and then put it right back together as you see fit.
Most professional eBook conversion and formatting firms will use an ePUB, or the constituent parts of the ePUB, to build the MOBI file. What does this mean for you, as a publisher? Well, think about it: if your formatting firm only gives you the MOBI file (cake!), and you later decide that you want to make changes—what do you do? You’re forced to go back to the same firm. You don’t have your source materials (your ingredients) any longer. I’ve even been told by some folks who’ve come to us that some companies will charge you as if it’s a brand-new book—a build from scratch, rather than simply revising the files that they must have in their archives.
So, don’t forget: you WANT an ePUB. Firstly, you never know when Amazon might decide to use ePUBs; you never know when you might want to change your ingredients; and third, heck—you’re paying for your eBook to be created. Make sure you get your own source files, for your future use.
And that way (yes, wait for it!)...you can have your Cake, and eat it, too.