How many books have ever been published in all of modern history? According to Google’s advanced algorithms, the answer is almost 130 million books. Yes, that number includes my books.
In order for Google Books to successfully catalog the world’s supply of printed knowledge, the company needed an estimate of the amount of books it needs to scan. That’s why Google set out to find the number.
First it had to define what a book is and agreed on ‘tome', an idealized bound volume. A tome can have millions of copies, like a bestseller or can exist in just one or two copies, such as a rare 'Tom Sawyer' first edition. ISBN, or International Standard Book Numbers, are designed to be unique identifiers for books but have only been around for about 40 years and are mostly used in Western countries.
The company poured over a billion raw records and used many and various algorithms to determine and discard duplicates. Of course the absolute number needs to be constantly, because new books are being published every day. In fact, I have a new one that should be out within about a month. "Flowers, Foreplay, Facelifts, Flatulence - A humorous romp through the four stages of relationships."