Short answers, pulled from the story.
A book is a written work of substantial length created by one or more authors, broadly classified into fiction and non-fiction. UNESCO in 1964 defined it as a non-periodical printed publication of at least 49 pages, excluding cover pages. The historian James Raven preferred a broader definition: a portable, durable, replicable and legible means of recording and disseminating information.
Google Books estimated in 2010 that roughly 130 million total unique books have been published.
The earliest forms included clay tablets, papyrus scrolls, and the codex. Cuneiform tablets were created circa 3200 BC during the Uruk period in modern-day Iraq, and Ancient Egyptian scribes wrote hieroglyphs on papyrus scrolls. The codex, with sheets bound along one edge, is the ancestor of the modern book.
The Chinese inventor Bi Sheng made movable type of earthenware around 1045, though no examples of his printing survive. Around 1450, Johannes Gutenberg independently invented movable type in Europe, along with innovations in casting type from a matrix and hand mould.
The first widely accepted ebook came in 1971 when Michael Hart started Project Gutenberg. Ebook readership spiked during the COVID-19 pandemic, and OverDrive reported 662 million digital items borrowed in 2023. U.S. audiobook sales reached 2.22 billion dollars in 2024, a 13 percent increase over the previous year, with an estimated 270 million monthly listeners worldwide.
An ISBN, or International Standard Book Number, is a unique identifier for every edition of every book from participating publishers, in use since 1970. It has four parts: a country code, a publisher code, a title code, and a check digit that can take values from 0 to 9 or X for 10. Bookland barcodes are derived from the ISBN by prefixing 978 and recalculating the check digit.
English-language publishing is dominated by the so-called Big Five publishers: Penguin Random House, Hachette Book Group, HarperCollins, Simon and Schuster, and Macmillan Publishers. They were estimated to make up almost 60 percent of the market for general-readership books in 2021.