Ebook

Ebook

An ebook is an electronic (or digital) version of a book. The term is used ambiguously to refer to either an individual work in a digital format, or a hardware device used to read books in digital format. Some users deprecate the second meaning in favour of the more precise "ebook device."

Though e-texts are available as digitally encoded books and the term is often used synonymously with the term ebook, that usage is deprecated. The term e-text is used for the more limited case of data in ASCII text format, while the more general e-book can be in a specialized (and, at times, proprietary) file format. An exception to this rule is the academic e-text, which commonly includes components such as facsimile images, apparatus criticus, and scholarly commentary on the work from one or more editors specially qualified to edit the author or work in question.

An ebook is commonly bundled by a publisher for distribution (as an ebook, an ezine, or a internet newspaper), whereas e-text is distributed in ASCII (or plain text), or in the case of academic works, in the form of discrete media such as compact discs. Metadata relating to the text are sometimes included with etext (though it appears more frequently with ebooks). Metadata commonly include details about author, title, publisher, and copyright date; less common are details regarding language, genre, relevant copyright conventions, etc.

Formats
The ebook community has many options when it comes to choosing a format for production. While the average end user might arguably simply want to read books, every format has its exponents and champions, and debates over "which format is best" can become intense. For the average end user to read a book, every format has its advantages and disadvantages. Formats available include, but are by no means limited to:

Image files
An ebook can be distributed as a sequence of images, one for each page. In this way, any image format can be used as an ebook format. This method of distribution produces files very much larger than all others, and also has the disadvantage that the user cannot select text, nor can the ebook be read by a screen reader. Distribution as images is most suitable for comic books, books about art, or other very visual works.

Rich Text Format
Published as an .rtf
A standard formalized by Microsoft Corporation for specifying formatting of documents. RTF files are actually ASCII files with special commands to indicate formatting information, such as fonts and margins.

Hyper Text Markup Language
Commonly known as HTML
HTML is the markup language used for most web pages. eBooks using HTML can be read using a standard browser (e.g., Mozilla, Firefox, or Microsoft Internet Explorer), with no need for special equipment.

CHM Format
Also known as Microsoft Compressed HTML Help
CHM format is an enhanced version of the HTML format. The main difference is the single file instead a set of files for HTML format.

PostScript
Published as an .ps
PostScript is a page description language used primarily in the electronic and desktop publishing areas for describing the contents of a printed page in a higher level than the actual output bitmap.

Standard Generalized Markup Language
Commonly known as SGML
Standardized metalanguage for the description of markup languages; a set of rules for using whatever markup vocabulary is adopted. This includes the Text Encoding

Initiative (TEI) standard.
eXtensible Markup Language
Published as an .xml
A subset of SGML constituting a particular text markup metalanguage for defining markup languages for the interchange of structured data. The Unicode Standard is the reference character set for XML content. XML is a trademark of the World Wide Web Consortium.

TeX
The TeX format is a popular academic format. TeX is a typesetting system written by Donald Knuth, especially for technical writing applications in the scientific communities of mathematics and computer science. TeX can typeset complex mathematical formulas, but is now also being used for many other typesetting tasks especially in template packages. Few people write in plain TeX any more. LaTeX is a TeX document preparation system. LaTeX offers programmable features and facilities for automating aspects of typesetting and desktop publishing, especially numbering and cross-referencing, tables and figures, page layout, bibliographies. LaTeX was originally written in 1984 by Leslie Lamport and has become a leading method for using TeX (current version: 2ε)

Portable Document Format
Published as a .pdf
A file format created by Adobe Systems, initially to provide a standard form for storing and editing printed publishable documents. Because documents in .pdf format can easily be seen and printed by users on a variety of computer and platform types, they are very common on the World Wide Web.

PDF files are created mainly using Adobe Acrobat, but Acrobat Capture and other Adobe products also support their creation, as do third-party products such as PDFCreator, OpenOffice.org, and FOP. Acrobat Reader (now simply called Adobe Reader) is Adobe's product used to view PDF files. PDF files typically contain product manuals, brochures, magazine articles, or flyers as they can embed fonts, images, and other documents. A PDF file contains one or more page images, each of which you can zoom in on or out from. The PDF format can include interactive elements such as buttons for forms entry and for triggering sound and Quicktime or AVI movies. Acrobat PDF files are optimized for the Web by rendering text before graphic images and hypertext links. Adobe's PDF-like eBook format is incorporated into their reader.

DjVu
Published as .djvu
DjVu is a file format that has been long in obscurity (in other words, since 1996), but that is starting to surface now that free tools to manipulate the files are available.

DjVu is a format that particularly excels in storing scanned images. There are even advanced compressors especially specializing in low-color images, such as text documents. Individual files may contain single pages, or they can be collections of multiple pages.

The images are divided in separate layers (such as multi-color, low-resolution, lossily-compressed background layer, and few-colors, high-resolution, tightly-compressed foreground layer), each compressed in best applicable method. The files are also designed to decompress very fast, even faster than vector-based formats.

The advantage of DjVu is that it is possible to take a high-resolution scan (300-400 DPI), good enough for both on-screen and printing, and store it very efficiently. Several dozens of 300 DPI black-and-white scans can be stored in less than a megabyte.

Microsoft
Published as an .lit
The MS reader uses patented ClearType® display technology. Navigation works with a keyboard, mouse, stylus, or through electronic bookmarks. The Catalogue Library records reader books in a personalized "home page". A user can add annotations and notes to any page, create large-print eBooks with a single command, or create free-form drawings in the reader pages. A built-in dictionary allows the user to look up words.

eReader (formerly Palm Digital Media)
Published as a .pdb
eReader is a program for viewing Palm Digital Media electronic books. Versions are available for PalmOS, PocketPC, Symbian OS, Windows, and Macintosh. The reader shows text one page at a time as paper books do. eReader supports embedded hyperlinks and images. Most eReader formatted books are encrypted, with the key being the purchaser's full name and credit card number.

Mobipocket
Published as a .prc
The Mobipocket Reader has a home page library. Readers can add blank pages in any part of a book and add free-hand drawings. Annotations — highlights, bookmarks, notes, and drawings — can be applied, organized, and recalled from a single location. Mobipocket Reader has electronic bookmarks, appearing in the page margins. Dictionaries allow users to look up definitions through a built-in Lookup function.
The reader has a full screen mode for the reading experience and has Microsoft ClearType® support. On Palm OS, readers can use sub-pixel rendering with the MobiType® font. Mobipocket Reader is the only eBook Reader running on nearly all PDA types (Palm OS, Pocket PC and Windows CE, Tablet PC, Casio BE-300, Psion, Symbian OS Smartphones, Franklin eBookMan) and PCs.

The Mobipocket eBook format based on the Open eBook standard using XHTML can include java-script and frames for a dynamic display, which makes Mobipocket the best solution for professional content such as medical reference eBooks and dictionaries. It also supports native SQL queries to be used with embedded databases.
The Mobipocket encryption system is not a password based system. Its DRM relies on the PDA hardware serial number.

Mobipocket also provides a free eNews service. A reader can subscribe to notable periodicals, or create custom channels. Software on the PC updates the subscriptions and sends them automatically to the PDA.

ExeBook
Published as an .exe
ExeBook is a compiler that produces an ebook file that, when executed, produces a simulated book onscreen, complete with page texture. The etext is encrypted as graphic images so that automatic text copying is very difficult. The fear of exe files picking up viruses, however, is hampering its acceptance.

DesktopAuthor
Published as an .exe and .dnl
DesktopAuthor is an electronic publishing suite that allows creation of digital web books with virtual turning pages. Digital web books of any epublication type can be written in this format, including ebrochures, ebooks, digital photo albums, ecards, digital diaries, online resumes, quizzes, exams, tests, forms and surveys. DesktopAuthor packages the ebook into a ".dnl" or ".exe" book. Each can be a single, plain stand-alone executable file which does not require any other programs to view it. DNL files can be viewed inside a web browser or stand-alone via the DNL Reader.
Comparison with printed books

Advantages
Text can be searched, except when represented in the form of images.
Take up little space.

Hundreds (or thousands) may be carried together on one device.
Approximately 500 average ebooks can be stored on one CD (equivalent to several shelves' worth of print books)

Because they take up little space, eBooks can be offered indefinitely, with no 'out of print' date, allowing authors to continue to earn royalties indefinitely (copyright law permiting), and allowing readers to find older works by favorite readers.

Ebooks may be read in low light or even total darkness, with a back-lit device.
Type size and type face may be adjusted. However, enlarging e.g. a PDF document magnifies the text but preserves the original layout and spacing; a practical limit on zooming follows from the requirement to keep a text column within the width of the screen (otherwise horizontal scrolling would be needed during and after reading each line, which would be very cumbersome). However, tagged PDFs can be reflowed in Acrobat 6 and 7, eliminating the horizontal-scrolling problem in zoomed PDFs. For more on zooming in, see Electronic maps.

Can be used with text-to-speech software.

Readily reformatted for independent platforms.

Instantly copied

When a backup is kept in a remote place, cannot be lost by fire, etc.
Once distributed, elimination is hard to impossible.

Distributed at low cost.

Distributed instantly, allowing readers to begin reading at once, without the need to visit a bookstore

Simultaneously share book (if networked).

Errors may be easily corrected with downloadable lists of errata or simply with corrected text. (This can also be an advantage for printed books, in different circumstances.)

At the moment, ebooks are commonly published by independent publishing houses, which can mean greater editorial and authorial freedom and more room for experimentation.

An inexpensive format for works that require color.

An excellent choice of format for works that benefit from search and cross-reference capabilities, such as dictionaries, reference works, certain kinds of textbooks.

Disadvantages
From the user's point of view:

Can be incompatible with new or replacement hardware or software

Require care in handling and storage of the files, to avoid damage or loss

Reading can be hard on the eyes

Lacks the quality of a print book as an item

From the publisher/author's point of view:
Can in some cases be hacked, or disseminated without approval from the author or publisher (some formats are more susceptible to this than others)

Not normally a good format choice for works that have extensive and/or large illustrations, such as works in art history, photography, large maps, etc.

Print book Advantages
Less eye strain over extended reading time

If small, very portable.

Usable in adverse environmental conditions.

Robust and durable.

Readable when severely damaged.

Requires no power source, and no alternative reading device like a PC or a palmtop.

Errors are "forever"; this unchangeability sometimes adds to its value.

Has more value as "collector's items," e.g., first editions

At the moment, print books are primarily published by established houses including
numerous international conglomerates, which can result in greater funds available for promotion of a title.

Disadvantages
From the user's point of view: Can be priced in a way that inhibits availability

From the user's and author's point of view: Can be put out of print and made unavailable to readers

From the author's point of view: Can be difficult to get a publisher to amend errata
Can be an awkward format for reference works or works that have many internal crossreferences.

An expensive format for works that require color, since color printing commonly requires several passes of paper through the press (one pass per color).