[custom_adv] A high-rise building is a tall building, as opposed to a low-rise building and is defined by its height differently in various jurisdictions. [custom_adv] It is used as a residential, office building, or other functions including hotel, retail, or with multiple purposes combined. [custom_adv] High-rise buildings became possible with the invention of the elevator (lift) and less expensive, more abundant building materials. The materials used for the structural system of high-rise buildings are reinforced concrete and steel. [custom_adv] Most North American style skyscrapers have a steel frame, while residential blocks are usually constructed of concrete. There is no clear difference between a tower block and a skyscraper, although a building with fifty or more stories is generally considered a skyscraper.