Doo wop is a kind of vocal harmony music performed by groups who became popular in the 1950s. Though sometimes considered a kind of rock, doo wop is more precisely a fusion of vocal R&B, gospel and jazz with the blues and pop structures, though until the 1960s, the lines separating rock from doo wop, R&B and other related styles were very blurry. Doo wop became the first style of R&B-derived music "to take shape, to define itself as something people recognized as new, different, strange, "theirs"" (emphasis in original). As doo wop grew more popular, more innovations were added, including the use of a bass lead vocalist, a practice that began with Jimmy Ricks of The Ravens. Doo wop performers were originally almost all black, but a few white and integrated groups soon became popular. These included a number of Italian-American groups such as Dion & the Belmonts, while others added female vocalists and even formed all-female groups in the nearly universally male field; these included The Queens and The Chantels.