Explanatory dictionaries give the following definition of the word “a book”: A book is a set or collection of written, printed, illustrated, or blank sheets, made of paper, parchment, or other material, usually fastened together to hinge at one side. A book produced in electronic format is known as an e-book.
When people could not write they passed knowledge from mouth to mouth. When writing systems were invented in ancient civilizations, nearly everything that could be written upon—stone, clay, tree bark, metal sheets—was used for writing.