How many books have been written since the first book was written?

There's no one definitive answer to this question as the number of books that have been written is constantly changing and increasing. However, according to the latest estimates from UNESCO (United Nations Educational, Scientific and Cultural Organization), there are approximately 130 million published books in the world today. However, this number is likely an underestimation as it does not account for books that have been self-published or are otherwise not in the public domain. Additionally, the number of books published each year is estimated to be around 2 million, meaning the number of books in the world is continuously increasing.