Quick Answer: A bookcase also called a bookshelf, is a piece of furniture with horizontal shelves, often in a cabinet, used to store books or other printed materials. Bookcases are used in private homes, public and university libraries, offices, schools, and bookstores. Bookcases range from small, low models the height of a table to high models reaching up to ceiling height. Shelves may be fixed or adjustable to different positions in the case. In rooms entirely devoted to the storage of books, such as libraries, they may be permanently fixed to the walls and/or floor. A bookcase may be fitted with glass doors that can be closed to protect the books from dust or moisture. Bookcase doors are almost always glazed with glass, so as to allow the spines of the books to be read. Especially valuable rare books may be kept in locked cases with wooden or glazed doors. A small bookshelf may also stand on some other piece of furniture, such as a desk or chest.