A book is a text-based work that is written or printed on a series of pages usually bounded together in covers. The pages in a book are sewn or glued together and then bound inside covers usually consisting of thick paper or pasteboard.

Books have changed drastically since they became widely used, but several chief characteristics of books have remained since their introduction long ago. Books have always served as a means of communication, something that is accomplished through a written alphabet and/or visual forms. Since the invention of the printing press in 1450, books were created to be widely circulated among numerous readers. Today they remain one of the most popular media for reading.

Books can contain virtually any content, as long as it can be printed on the pages, Works of literature, scholarship (including textbooks) and nonfiction contain the most common content for books. However plenty of other book types exist, such as cookbooks, songbooks, dictionaries, photography books, encyclopedias, etc. Recently, online books (called eBooks) have been gaining prominence and popularity, challenging the meaning of the word 'book' and also challenging print publishers for their business. (Photo: Wikimedia Commons)