Doo-wop is a style of vocal-based Rhythm and blues music popular in the mid- to late-1950s in America. The style was at first characterized by upbeat harmony vocals ("Gee," by the Crows, for example) that used nonsense syllables from which the name of the style is derived. The name was later extended to group harmony ballads. Examples of doo-wop can be found in the music of The Turbans, The Penguins, and Jackie & the Starlites.
See also Scat singing, Vocalese.