[custom_adv] A movie theater, cinema or cinema hall, also known as a picture house, the pictures, or the movies, is a building that contains auditoria for viewing films (also called movies) for entertainment. [custom_adv] Most, but not all, theaters are commercial operations catering to the general public, who attend by purchasing a ticket. Some movie theaters, however, are operated by non-profit organizations or societies that charge members a membership fee to view films. [custom_adv] The film is projected with a movie projector onto a large projection screen at the front of the auditorium while the dialogue, sounds and music are played through a number of wall-mounted speakers. [custom_adv] Since the 1970s, subwoofers have been used for low-pitched sounds. In the 2010s, most movie theaters are equipped for digital cinema projection, removing the need to create and transport a physical film print on a heavy reel. [custom_adv] A great variety of films are shown at cinemas, ranging from animated films to blockbusters to documentaries. The smallest movie theaters have a single viewing room with a single screen. [custom_adv] In the 2010s, most movie theaters had multiple screens. The largest theater complexes, which are called multiplexes—a concept developed in Canada in the 1950s — have up to thirty screens. The audience members often sit on padded seats, which in most theaters are set on a sloped floor, with the highest part at the rear of the theater.