A UNESCO conference in 1964 attempted to define a book for library purposes as
"a non-periodical printed publication of at least forty-nine pages, exclusive of cover pages". A single sheet within a codex book is a leaf, and each side of a leaf is a page. Writing or images can be printed or drawn on a book's pages.
In library and information science, a monograph is a book of one or more volumes which is not a serial such as a magazine, journal, or newspaper.
An avid reader or collector of books or a book lover is a bibliophile or colloquially, "bookworm".
A shop where books are bought and sold is a bookshop or bookstore. Books are also sold elsewhere. Books can also be borrowed from libraries. Google has estimated that as of 2010, approximately 130,000,000 distinct titles had been published. In some wealthier nations, the sale of printed books has decreased because of the use of e-books, though sales of e-books declined in the first half of 2015.
