When you are part of a company that is trying to digitize all the books in the world, the first question you often get is: “Just how many books are out there?”Well, it all depends on what exactly you mean by a “book.” We’re not going to count what library scientists call “works,” those elusive "distinct intellectual or artistic creations.” It makes sense to consider all editions of “Hamlet” separately, as we would like to distinguish between -- and scan -- books containing, for example, different forewords and commentaries.One definition of a book we find helpful inside Google when handling book metadata is a “tome,” an idealized bound volume. A tome can have millions of copies (e.g. a particular edition of “Angels and Demons” by Dan Brown) or can exist in just one or two copies (such as an obscure master’s thesis languishing in a university library). This is a convenient definition to work with, but it has drawbacks. For example, we count hardcover and paperback books produced from the same text twice, but treat several pamphlets bound together by a library as asean single book...
So after all is said and done, how many clusters does our algorithm come up with? The answer changes every time the computation is performed, as we accumulate more data and fine-tune the algorithm. The current number is around 210 million.Is that a final number of books in the world? Not quite. We still have to exclude non-books such as microforms (8 million), audio recordings (4.5 million), videos (2 million), maps (another 2 million), t-shirts with ISBNs (about one thousand), turkey probes (1, added to a library catalog as an April Fools joke), and other items for which we receive catalog entries.Counting only things that are printed and bound, we arrive at about 146 million. This is our best answer today. It will change as we get more data and become more adept at interpreting what we already have...
After we exclude serials, we can finally count all the books in the world. There are 129,864,880 of them.