A dog ear is a folded down corner of a book page. The name refers to the ears of many breeds of domestic dog flapping over. A dog ear can serve as a bookmark. Dog-earing is also commonly used to mark a section or phrase in a book that one finds to be important or of personal meaning. Other names for this practice include page folding and corner turning. The practice is generally frowned upon by those that want to preserve books in their original condition. It is also sometimes used to keep sheets of paper together, in the absence of a stapler or paper clip.