An illustrated song is a type of performance art and was a popular form of entertainment in the early 20th century in the United States. Live performers (usually both a pianist and a vocalist) and music recordings were both used by different venues (vaudeville houses first and later in nickelodeons) to accompany still images projected from glass slides. This allowed the images to be painted in color by hand. A single song was usually accompanied by 12 to 16 different images that sequentially "illustrated" the lyrics. Projection booths used either stereopticons with two projectors or machines that combined projection of both slides and moving pictures. Illustrated songs often preceded silent films and/or took place during reel changes, but some venues relied principally on illustrated songs