Then came PDF format, and suddenly a new world was opened. The page of a book - complete with headers, footers, page numbering, graphics, and other formatting features, could be perfectly matched on a computer screen. A PDF ebook was literally page for page identical to the print copy. For several years the PDF format was the standard for an ebook. If someone said they had an ebook, it was expected that they had a PDF file which exactly matched the print book's layout and format.
Then came the world of e-readers and tablets. These systems could sometimes show PDFs - but many times they could not. Instead, they used a brand new format, called ePUB. This ePUB format was an ebook format specifically designed for ebook readers. The Amazon Kindle happens to use a format called MOBI, but really it is just a variant of ePUB. So in both cases they are specialized formats meant for ebook readers.
Here is the difference between a PDF and an EPUB / MOBI, in terms of what a user sees.
Let's use an example from one of my books.
In the image below, this is the same page from the same book on Low Carb Charts. The left side shows the PDF version - this is in essence an exact replica of what the physical book page looks like. It has a header, a footer, and a table layout.
The right side shows the EPUB / MOBI version. There are no headers and footers in an EPUB, because there are no set "pages". The text flows smoothly throughout a chapter, and the user makes the font larger and smaller as they wish. A chapter might take up 5 "pages" or it might take up 50 "pages" depending on the font size the user chooses, the screen size of their reader, and a variety of other factors.
Many EPUB / MOBI readers are black and white only, and wouldn't show any color. This PC reader I'm using does show color, as you can see in the header. Many EPUB / MOBI readers don't do tables at all, so it's best not to include them for cross-platform compatibility. Amazon will refuse an ebook if it realizes it has tables in it; if you want to be on the Kindle, make your file table-free.
On an EPUB / MOBI what the person sees is the content of the book in a free flowing stream. Yes, if you're writing a novel you can put in chapter breaks so each chapter of a novel starts on a fresh page. But other than that the text within a chapter flows smoothly without any page breaks.
There are no page numbers in an EPUB, because you have no idea how big a page is going to be from reader to reader. The person would use a 'bookmark' feature to mark a page and return to it later. They wouldn't try to remember a page number, as there is no such thing.
Most ebook readers and apps have a built in table of contents button that lets the person easily hop from chapter to chapter if they want to. These readers and apps also provide search features, so a person could search for a word or phrase to get to that area quickly. There is no longer any need for an index.
So in modern times, yes certainly create an ebook's PDF file for historical reasons. Some people do still use PDF files.
However, most people who read ebooks prefer the EPUB or MOBI format, as it works more smoothly with their various ebook readers and tablets. It allows them more customization.
And finally, the EPUB / MOBI files tend to be much smaller than PDF files, so the person can fit more of them on their ebook reading device.
I explain in these pages here, step by step, how to make an EPUB and MOBI file from your starting Word (or Word-equivalent) document.
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