Crossover is a term applied to musical works or performers who appeal to different types of audience, for example (especially in the United States) by appearing on two or more of the record charts which track differing musical styles or genres. If the second chart combines genres, such as a "Hot 100" list, the work is not a crossover.
In some contexts the term "crossover" can have negative connotations associated with cultural appropriation, implying the dilution of a music's distinctive qualities to appeal to mass tastes. For example, in the early years of rock and roll, many songs originally recorded by African-American musicians were re-recorded by white artists such as Pat Boone in a more toned-down style, often with changed lyrics, that lacked the hard edge of the original versions. These covers were popular with a much broader audience.
In practice crossover frequently results from the appearance of the music in question in a film soundtrack. For instance, Sacred Harp music experienced a spurt of crossover popularity as a result of its appearance in the 2003 film Cold Mountain, and bluegrass music experienced a revival due to the reception of 2000's O Brother, Where Art Thou?. Even atonal music, which tends to be less popular among classical enthusiasts, has a kind of crossover niche, since it is widely used in film-making and television production scores "to depict an approaching menace", as noted by Charles Rosen.
Classical crossover broadly encompasses both classical music that has become popularized and a wide variety of popular music forms performed in a classical manner or by classical artists. It can also refer to collaborations between classical and popular performers, as well as music that blends elements of classical music (including operatic and symphonic) with popular music (including pop, rock, middle of the road, and Latin, among other types). Pop vocalists and musicians, opera singers, classical instrumentalists, and occasionally rock groups primarily perform classical crossover. Although long a common phenomenon in the music world, the name "classical crossover" was coined by record companies in the 1980s. It has gained in popularity since the 1990s and has acquired its own Billboard chart.