Traditional pop (also classic pop or pop standards) music consists of Western (and particularly American) popular music that generally pre-dates the advent of rock and roll in the mid-1950s. Traditional/classic pop music is generally regarded as having existed between the mid-1940s and mid-1950s. AllMusic defines traditional pop as "post-big band and pre-rock & roll pop music." This definition is disputed by many scholars, however, as many of the most popular works of Cole Porter and those of George and Ira Gershwin pre-date World War II, while the works of Irving Berlin and Jerome Kern date to World War I.