[Louis] Armstrong had been to New York to play with Fletcher Henderson, who had one of the best dance bands of the period. It was bigger than the usual New Orleans group, and because it had more instruments written arrangements were necessary. There were three trumpets, a trombone, and three saxophones, and it was not possible for all these men to memorize or merely improvise their different parts as was done in New Orleans. So Henderson and his chief arranger, Don Redman, both schooled musicians, wrote the music for the band to play, leaving gaps or choruses for improvisation. The rhythmic effect created by Armstrong in his solo choruses was stirring--an extra lift above and beyond the basic beat--and this sort of thing was what became known as "swinging." << less