Unlike a paper book, an ebook can be delivered instantly to your ereader device or home computer. The Amazon Kindle and Barnes & Noble's Nook are both capable of allowing the purchase and download of a new book within minutes or seconds. Unless you're in the bookstore picking it up, no paper book can match the quick gratification of an ebook.
Despite its convenience, the ebook has a major drawback. Most commercial ebooks are sold with strict digital rights management (DRM) restrictions upon them, preventing owners from lending or selling books, and sometimes from transferring a book from one device to another of their own. This has led to complaints that you don't really own your book, but only lease it from the bookseller for a period of time.
On the other hand, millions of out-of-copyright books and even new copyrighted books are available to readers for free download and distribution with no DRM at all.
No library of printed texts is as portable as an etext library. Ereaders weigh less than a pound on average, and each text added to the system adds no weight. It is simple to carry a virtual library of thousands of books. The same number of books in printed form could easily fill a moving van.
Currently the industry is debating whether ebooks or paper books are more environmentally friendly. Paper books are made of trees or other cellulose. They are printed using an assembly-line system that involves multiple toxic chemicals, then driven to a bookstore where a customer purchases them. A single book can have quite a carbon footprint. Virtual books seem to have no environmental problems.
It is the ereader that has some environmental problems. Its manufacture requires the extraction of rare-earth elements, burning of fossil fuels and transportation to stores or homes. Comparing ereaders with traditional books, up to about 100 books would have to be purchased and stored on the ereader in order for its manufacture to be offset by energy and pollution saved.
Ebooks have enormous publication differences. Many ebooks are formatted by contractors, not publishers. They can be quickly edited and prepared for release in an ebook format, eliminating long publication waits. Because you are downloading a pattern of dots and dashes and not picking up a physical object, the size of a print run becomes meaningless. In addition, publishers incur no production costs outside of editing and typesetting, nor do they incur transportation costs or remaindered-book loss.
Writers are starting to see the marketing potential in releasing free ebooks of older works when promoting pay versions of new books. At the Baen Online Library, dozens of writers have donated old works for free download to anyone. Cory Doctorow, co-editor of Boing Boing and author of several fantasy novels, releases all of his novels as etexts at the same time they are being printed. Writers who participate in this sort of marketing scheme all agree that it seems to give a boost to their later book sales.