Charles Parker Jr. (August 29, 1920 – March 12, 1955), also referred to by his nicknames Yardbird or simply Bird, was an American jazz saxophonist 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. Parker was a blazingly fast virtuoso and introduced revolutionary harmonic ideas into jazz, including rapid passing chords, new variants of altered chords, and chord substitutions. Primarily a player of the alto saxophone, Bird's tone ranged from clean and penetrating to sweet and somber.