Jazz is a music genre that originated from African American communities of New Orleans in the United States during the late 19th and early 20th centuries. Since the 1930s during the jazz age, jazz has become recognized as a major form of musical expression following George Gershwin and other notable composers. It emerged in the form of independent traditional and popular musical styles, all linked by the common bonds of African American and European American musical parentage with a performance orientation. Jazz is characterized by swing and blue notes, call and response vocals, polyrhythms and improvisation. Jazz has roots in West African cultural and musical expression, and in African American music traditions including blues and ragtime, as well as European military band music. Although the foundation of jazz is deeply rooted within the black experience of the United States, different cultures have contributed their own experience and styles to the art form as well. Intellectuals around the world have hailed jazz as "one of Americas original art forms". As jazz spread around the world, it drew on different national, regional, and local musical cultures, which gave rise to many distinctive styles. New Orleans jazz began in the early 1910s, combining earlier brass-band marches, French quadrilles, biguine, ragtime and blues with collective polyphonic improvisation. In the 1930s, heavily arranged dance-oriented swing big bands, Kansas City jazz, a hard-swinging, bluesy, improvisational style and Gypsy jazz (a style that emphasized musette waltzes) were the prominent styles. Bebop emerged in the 1940s, shifting jazz from danceable popular music toward a more challenging "musicians music" which was played at faster tempos and used more chord-based improvisation. Cool jazz developed in the end of the 1940s, introducing calmer, smoother sounds and long, linear melodic lines. The 1950s saw the emergence of free jazz, which explored playing without regular meter, beat and formal structures, and in the mid-1950s, hard bop emerged, which introduced influences from rhythm and blues, gospel, and blues, especially in the saxophone and piano playing. Modal jazz developed in the late 1950s, using the mode, or musical scale, as the basis of musical structure and improvisation. Jazz-rock fusion appeared in the late 1960s and early 1970s, combining jazz improvisation with rock musics rhythms, electric instruments and the highly amplified stage sound. In the early 1980s, a commercial form of jazz fusion called smooth jazz became successful, garnering significant radio airplay. Other styles and genres abound in the 2000s, such as Latin and Afro-Cuban jazz.