Popular or pop music is music that appeals either to a wide cross section of the public or to sizable subdivisions within the larger public based on age, region, or ethnic background (e.g., teenagers, southerners, Mexican Americans). U.S. pop music today encompasses styles as diverse as blues, country, Tejano, salsa, jazz, rock, reggae, punk, hip-hop, and dance. The word pop has also been used to distinguish popular music from classical music, which is written primarily for ballet, opera, ensemble, or symphony. As various subcultures have intersected, U.S. popular music has developed organically, constantly creating new forms and reinvigorating older musical styles.