Charles Parker Jr., nicknamed "Bird" or "Yardbird", was an American jazz saxophonist, bandleader, and composer. Parker was a highly influential soloist and leading figure in the development of bebop, a form of jazz characterized by fast tempos, virtuosic technique, and advanced harmonies. He was a virtuoso and introduced revolutionary rhythmic and harmonic ideas into jazz, including rapid passing chords, new variants of altered chords, and chord substitutions. Parker primarily played the alto saxophone.