Ebooks (or e-books, for electronic books) are just books, but made for the Information Age. So, they are not more electronic than they are virtual, or computer, or paperless books. More essentially, they are the terminal point of an evolutionary process which also includes the so-called desktop publishing, where classic typography means were gradually substituted with computational ones (not electronic, please, just computational). At the end of the process, also the final results of the book-production process become immaterial.
Being immaterial, an ebook is in principle free from the constraints of the paper-based version: however, human legacy – like the habits built up in half millennium of printed books (and several millennium of written ones) – brings about some desired/expected properties that do not strictly depend on the nature of ebooks – like the page-based structure super-imposed on the sequential structure of a text.
New properties, of course, become available and even desirable:
In the overall, one may surely miss fascinating and romantic situations like looking for a rare text in a peripheral street market, sniffing the smell of a new paper book, or feeling the reassuring weight of your preferred books in your bag when starting for a long travel. However, some of the advantages of ebooks – in particular, when looking your wooden home library already more than full, or when you have to choose which books to bring with you among the thirty-five you would possibly like to read when travelling around – are undeniable. There are already several nice things that you can do with an ebook — and you cannot with a book. Even though things will just improve over time under that aspect, cost is definitely among the benefits of ebooks right now.
So, ebooks are now among us, and this is definitely good news for any honest bookworm.
[See ebooks on Wikipedia]
Sharing ebooks among different devices of diverse sorts from distinct vendors requires shared formats. The possibility of shared formats to spread widely and to survive over time is bound to the availability of standards for shared ebook formats. While a single standard would in principle simplify reader's life, a limited number of competing standards have the chance of promoting both the provision of different features and the test of new properties.
The most meaningful formats for ebooks today are
PDF (Portable Document Format) is not a specific format for ebooks, but is instead born generically for electronic documents. PDF is born for having documents that retain their form whether they are read onscreen by any computational device (computers, tablets, smartphones) or they are printed on any sort of printer.
A PDF document can contain text and pictures in almost any format: so, pages are typically recorded in textual format (then, the text can be searched), but sometimes they can also contain pages as pictures – as in the case of scanned documents, where the textual form is not directly available, and so not searchable. Nowadays, scanned documents are typically either made textual via OCR techniques, or distributed in DjVu form.
[See PDF on Wikipedia]
The EPUB format is an open standard for ebooks defined by the International Digital Publishing Forum (IDPF). This is the de facto standard for ebooks, at least for those where the text is more important than the pagination. All ebook readers can read and display the EPUB format.
Being unconcerned with pagination, EPUB is the best choice for ebooks to be read on a wide range of different devices, where screen size and resolution may largely vary. In fact, ebook readers can let human readers choose the font size and kind, the page format (two-pages, one-page), and accordingly adapt to the screen in use.
By the way, EPUB is my format of choice for ebooks, whenever PDF is not necessary.
[See EPUB onWikipedia]
AZW & Mobipocket
These are essential two different Amazon formats for ebooks, with different DRM schemes. While Mobipocket is an old format (and the corresponding company is Amazon-owned), AZW is basically the Amazon format for Kindle, the Amazon ebook reader.
This format does not add much to the EPUB platform, and exists almost only for bounding readers to the Kindle/Amazon platform, and to DRM-protect ebooks. This is why I use this format only when strictly necessary. There, my only real interest is removing DRM from Kindle ebooks, translating them into the standard EPUB format, and so read them in the way I prefer. Don't tell me this is illegal: I legally buy ebooks from Amazon, then they are mine to read them with any device I like, in whatever format I like. Amazon will not rule my life as an bookworm.
DjVu is a format specialised for storing scanned documents, so that their digital form is a sequence of images rather than a textual one. Old books and documents that cannot be easily reconstructed in their textual form can be first of all scanned and made available in DjVu format. This format is not so widely recognised, but there are dedicated readers for many platforms, which can also translate DjVu documents into PDF ones – typically heavier, but easily read everywhere.
[See DjVu on Wikipedia]
For a comparison on ebook formats, one may read the following articles:
While Adobe Acrobat, Apple Preview ("Anteprima", in Italian) and other similar beasts are the typical way that everybody uses for PDF documents and ebooks, finding the right tool for handling (storing, reading, converting) ebooks is a little trickier matter. In the following, I mean to maintain a list of ebook related software packages and apps that could be of use managing ebooks on various sorts of devices. I will for now forget about dedicated eReaders, since I have no interest for now in specialised devices.
Calibre is currently the most versatile and all-powerful tool in the list. It handles almost all the ebooks formats (some problems with DjVu), the conversions among them, metadata research and modification, libraries, and also helps governing handheld devices, like tablet and smartphones, keeping your ebook libraries dutifully synchronised. While it is not actually a nice piece of software from an interface and aesthetic viewpoint, I recommend giving it a try before anything else.
Calibre is available for Windows, Mac OS X and Linux platforms.
[See Calibre on Wikipedia]
[See Stanza on Wikipedia]