Not long ago, reading a book on your telephone was science fiction. Computers have transformed the making, promotion and reading of books and magazines. Publishers use computers to design and produce hard-copy books and e-books, market books to readers and track sales. Readers download books and magazines to their phones, laptops and tablets to read wherever they go.

Behold the E-book

Digital books make up 30 percent of the book-publishing marketplace at the time of publication. Special-interest magazines for niche markets thrive online, where they save on hard-copy printing and paper costs. Digital publishing makes it easier for writers to release their work without a traditional publisher's support. A writer can release a digital book with no expense but time and no more equipment than the software on her laptop.

Designing the Word

Computers make designing books both faster and more complex. Designers and self-published writers use page-layout and illustration software to pull together illustrations, cover designs, layouts and typefaces in a fraction of the time it would take by hand. If the book needs revision, it's easy to revise and make changes to digital files. Publishers can't simply convert the design and pagination of their hard-copy releases to a digital version. For maximum flexibility, they use software to generate versions that read well on laptops, tablets, phones and e-readers.

Going to Market

In publishing, as in most industries, computers and the Internet are vital marketing tools. Publishers email customers with newsletters about new releases. Magazines announce when the next issue goes on sale. Publishers and authors rely on social media for promotion -- tweeting about new books, creating Facebook pages or promoting books on GoodReads. Self-published authors use email and social media to publicize their work or send out digital copies to book-review websites.

The Booksellers

When Amazon sold its first book in 1995, selling books online was a radical idea. In the 21st century, it's routine. Even brick-and-mortar stores do a lot of online business, and publishers offer books on their own websites. Online bookselling works well for publishers who can sell to readers anywhere in the world, but it's had the side effect of forcing many independent bookstores and a national chain to shut their doors.