A cinema organ is a pipe organ originally designed specifically for imitation of an orchestra.
Theatre organs took the place of the orchestra when installed in a cinema (movie theatre) during the heyday of silent films. Most theatre organs were modelled after the style originally devised by Robert Hope-Jones, which he called a "unit orchestra".
Such instruments were typically built to provide the greatest possible variety of timbres with the fewest possible pipes, and often had pianos and other percussion instruments built in, as well as a variety of sound effects such as a siren.
Theatre organs are usually identified by their distinctive horseshoe-shaped consoles, which are frequently painted white with gold trim. An original example is the 3/13 Barton from Ann Arbor's historic Michigan Theatre. The organ was installed in 1927 and is currently played daily before most film screenings. There were over 7,000 such organs installed in American theatres from 1915 to 1933, but fewer than 40 original instruments remain in their original theatres.