An e-book (also referred to as an electronic book, digital book, or e-edition) is a book-length publication in digital form, consisting of text, images, or both, and produced on, published through, and readable on computers or other electronic devices. Sometimes the equivalent of a conventional printed book, e-books can also be born digital. The Oxford Dictionary of English defines the e-book as "an electronic version of a printed book," but e-books can and do exist without any printed equivalent. E-books are usually read on dedicated e-book readers or general purpose computer tablets. Personal computers and many mobile phones (most smart phones) can also be used to read e-books.
Source: Wikipedia. (2012). E-book. Retrieved from http://en.wikipedia.org/wiki/E-book