is considered one of the most influential jazz vocalists of the 20th Century.

With a vocal range spanning three octaves, she was noted for her purity of tone, near faultless phrasing and intonation, and a "horn-like" improvisational ability, particularly in her scat singing. She is widely considered to have been one of the supreme interpreters of the Great American Songbook.

Over a recording career that lasted fifty-seven years, she was the winner of thirteen Grammy Awards, and was awarded the National Medal of Art by Ronald Reagan and the Presidential Medal of Freedom by George H. W. Bush.