Some experts predict that ebooks will someday be free to consumers because ads will be placed within the content to support publication. The ads will generate the revenue, while readers reap the benefit of free books.
Interestingly, most modern publishing contracts state that publishers may not sell advertising with their books. This restriction appeared in the early 1970s, when cigarette companies started buying insert ads in paperbacks. Authors objected. In time, advertising restrictions became standard clauses in publishing contracts.
Advertising in ebooks may indeed be a new way for publishers to increase their profits from ebooks, if authors begin to agree to ad placement. If you are interested in placing ads in your ebooks, watch this video showing seven ways you can feature ads in an ebook.