In the early 1900s the word Jazz was used to mean most kinds of American popular and dance music. Since the 1920s, however, Jazz has usually signified a tradition in  Afro- American music that began as folk music in the South and developed gradually into a sophisticated modern art. Unique features of Jazz are its sounds and its rhythms. Its goal has been to express strongly felt emotions. Jazz features syncopated rhythms-  rhythms with stimulating, offbeat accents. The several instruments in Jazz groups are usually played in separate rhythms that unite to create an uplifting effect.