A "rack" is a framework or structure used for holding or storing items. It can be made from various materials, such as wood, metal, or plastic, and comes in different shapes and sizes. Racks are commonly used in homes, offices, and warehouses to organize and display products, tools, or equipment. There are many types of racks, including bookshelves for storing books, clothes racks for hanging garments, and bike racks for parking bicycles. Each type serves a specific purpose, helping to maximize space and improve accessibility to the items stored on them.