The development of jazz can be seen as part of the larger continuum of American popular music, especially dance music. In the twenties, jazz became the hottest new thing in dance music, much as ragtime had at the turn of the century, and as rhythm and blues in the forties, rock in the fifties, and disco in the sies. But two characteristics distinguish jazz from other dance music. The first is improvisation, the changing of a musical phrase according to the player’’s inspiration. Like all artists, jazz musicians strive for an individual style, and the improvised or paraphrased solo is a jazz musician’’s main opportunity to display his or her individuality. In early jazz, musicians often improvised melodies collectively, thus creating a kind of polyphony. There was little soloing as such, although some New Orleans players, particularly cornet player Buddy Bolden, achieved local fame for their ability to improvise a solo. Later the idea of the chorus-long or multi-chorus solo took hold. Louis Armstrong’’s instrumental brilliance, demonstrated through extended solos, was a major influence in this development. Even in the early twenties, however, some jazz bands had featured soloists. Similarly, show orchestras and carnival bands often included one or two such "get-off" musicians. Unimprovised, completely structured jazz does exist, but the ability of the best jazz musicians to create music of great cohesion and beauty during a performance has been a hallmark of the music and its major source of inspiration and change. The second distinguishing characteristic of jazz is a rhythmic drive that was initially called "hot" and later "swing". In playing hot, a musician consciously departs from strict meter to create a relaxed sense of phrasing that also emphasizes the underlying rhythms. ("Rough" tone and use of moderate vibrato also contributes to a hot sound.) Not all jazz is hot, however, many early bands played unadorned published arrangements of popular songs. Still, the proclivity (倾向) to play hot distinguished the jazz musician from other instrumentalists. The word "get-off (Line 2, Para. 3) could be replaced by________.