Question: Is it common practice for authors to donate books in order to gain exposure?
Answer: I’m not aware of studies or official figures on this topic, but in my experience, some sort of donation is fairly common. Sometimes books are donated directly to libraries. Sometimes they are donated to reviewers, or library or subject area publications for review. These copies often make their way into libraries as well. We do get some donated books from authors or publishers here at the Alaska State Library. We sometimes add donated titles to our own collection. However, we have limited space and a fairly strict collection development policy, so often we are unable to keep donated titles. We also sometimes pass donations onto to other libraries, when we determine that they might be of better use there.
I have worked in other libraries, too, and I’ve noticed that libraries are often unable to add donated books to their collections because they don’t fit within the libraries’ collection development practices. This practice may be somewhat more lax in public libraries, as compared to research libraries. If you are considering donating a book to libraries, I encourage you to start by sending an email or letter, and only send actual copies when the library indicates that they can add the title.