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How Does an E-Book Work?


Unlike a printed book, an e-book consists solely of computer data. To read it, you download it to a digital device such as an Amazon Kindle, PC or tablet computer, which displays the e-book contents on a screen.

Digital File

An e-book is a data file similar in content and structure as a word-processing document; it contains all the text and images of a book, stored in electronic format. E-books come in three main file types:

  • mobi: for Amazon Kindle and related devices
  • epub: for Nook, Kobi and other e-book readers
  • PDF: the Portable Document Format developed by Adobe

E-book files contain not just raw text but also typography that gives an e-book page the appearance of a printed book. Most e-book reading devices read either mobi or epub formats but not both. Some devices also accommodate PDFs.

Purchasing, Downloading and Reading

You can buy e-books from a bookseller’s website, such as Amazon or Barnes and Noble; in addition, some publishers and authors sell e-books directly from their own sites. You can also purchase an e-book using the reader device itself. After you pay for the e-book, you must download it to the device before you can read it. When the download is finished, the e-book becomes part of the device’s internal library; the device shows the title and cover art for all e-book titles you own. You open the e-book by tapping on its graphic icon. The device displays the content, typically one page at a time. Turn pages by tapping buttons on the e-book reader. The reader device keeps track of the last read page for all the e-books you’re reading, so you can “put down” one e-book and read another anytime without losing your place.

Lost or Stolen E-Book Readers

Although your e-books reside on your device, the bookseller maintains a database of all its e-books and the customers who purchased them. Most e-book sellers allow the replacement of books lost to theft, broken devices and similar problems. If you lose the e-book reader, you can download your e-books onto another device. The bookseller serves as a “master backup” of your e-book titles.

Digital Rights Management

Many e-books, especially those put out by major publishing houses, come with software called Digital Rights Management, a technology designed to prevent illegal copying. The DRM is part of the e-book file and effectively “locks” the book’s contents. Under most circumstances, it doesn’t intrude on your reading experience or otherwise make itself known. The DRM will, however, prevent you from copying or modifying the book. In rare instances, customers’ e-books have vanished when a publisher went out of business; the DRM was no longer valid, causing the books to erase themselves.

Variety of Devices

In addition to dedicated e-book devices such as the Kindle, Nook and Kobo, you can obtain free reader apps for your smartphone, tablet computer and PC. These alternatives open e-books to those who have one of these devices and don’t care to buy a dedicated reader. The reader apps “sync” with each other, so if you finish a chapter on your desktop PC at home, you can pick up at the same place on your tablet PC on your train commute to work.

Ebook Prices

Many popular e-book titles are priced at under $10, usually less than the equivalent printed version. You can find many bargains offered at between $.99 and $5.99, including e-books by new and self-published authors looking to entice readers with low prices. Some titles are available for free as part of a publisher’s sales promotion.

About the Author

Chicago native J.T. Barett has a Bachelor of Science in physics from Northeastern Illinois University and has been writing since 1991. He has contributed to "Foresight Update," a nanotechnology newsletter from the Foresight Institute. He also contributed to the book, "Nanotechnology: Molecular Speculations on Global Abundance."