Charlie Parker (1920–1955), nicknamed 'Bird' or 'Yardbird,' was a revolutionary alto saxophonist and one of the principal architects of bebop. His virtuosic technique, harmonic sophistication, and melodic invention transformed jazz in the 1940s. Parker's compositions—including 'Ornithology,' 'Ko-Ko,' 'Confirmation,' and 'Donna Lee'—became essential repertoire for jazz musicians. His influence on jazz improvisation and composition is so profound that virtually every jazz musician since has been shaped by his innovations. Parker's works have been arranged for big bands by many leading arrangers.