What is a “book”?
Back at the end of 2010, I started keeping a log of all the books I read over the course of the year. At the time, I was mostly reading used hardcovers bought cheaply from Amazon (at least partly to upgrade my library of aging and yellowing paperbacks), and listening to free LibriVox audiobooks on the iPod. Hardcovers and audiobooks are pretty clearly books, and hardcovers have the advantage of being easily shared with other people in the house.
2013 was the year that I finally started reading on an iPad. It’s been great, so much more convenient in so many ways. Reading books on a notebook computer is difficult, because it’s too easy to get distracted by the immense-but-ephemeral literature of the Web, while the opposite seems to be true on a tablet computer.
Yet the iPad can display many kinds of books, and specific book niches have different ecosystems. EPUB3, Amazon Kindle, and Apple iBooks are the most well-known ebook formats, but digital editions of art- and chart-heavy RPG and game rulebooks are more frequently distributed as PDFs at Paizo or DriveThruRPG. If a book is a book, and an audiobook of a book is a book, and an ebook of a book is a book, and a PDF of a book is a book, are not most sustained texts in these formats “books”? This is a much fuzzier definition of “book”. Say, is a series of instructional blog posts on a sustained topic, redistributed as a 50-page PDF, a book? I guess so.
Podcasts with a group of hosts, like Conlangery, resemble radio shows more than books. But The History of Rome had the single author reading a prepared script, like a serialized book in audiobook form. And it was certainly a sustained work, unfolding over five years, a 675,000-word script, and 74 hours. For comparison, Edward Gibbon’s Decline and Fall of the Roman Empire becomes a 120-hour audiobook.
I expect “books” will get weirder before the end.