A book is a collection of paper, parchment or other material with text, pictures, or both written on them, usually bound together along one edge within covers. Each side of a sheet is called a page and a single sheet within a book may be called a leaf. A book is also a literary work or a main division of such a work. A book produced in electronic format is known as an e-book. In library and information science, a book is called a monograph to distinguish it from serial periodicals such as magazines, journals or newspapers.