Entitled: "Hurly-Burly Extravaganza and Refined Vaudeville" lithograph poster created by Courier Lithographing Company, 1899. Kelly & Ashby were a comedy duo who specialized in acrobatics. A typical vaudeville performance is made up of a series of separate, unrelated acts grouped together on a common bill. Types of acts have included popular and classical musicians, singers, dancers, comedians, trained animals, magicians, female and male impersonators, acrobats, illustrated songs, jugglers, one act plays or scenes from plays, athletes, lecturing celebrities, minstrels, and movies. Vaudeville developed from many sources, including the concert saloon, minstrels, freak shows, dime museums, and literary American burlesque. Called "the heart of American show business," vaudeville was one of the most popular types of entertainment in North America for several decades.