The document discusses the history and evolution of rhythm and blues (R&B) music from the late 1940s to the present. It notes that R&B originated as an African-American urban sound that combined blues and jazz. In the late 1940s, R&B became popular for its danceable, rocking and jazz-based beats. By the 1950s, R&B began to define the sound of rock and roll, while the 1960s saw the incorporation of soul music. Subsequent decades saw the integration of disco, funk, pop and other genres into the R&B category. Today, R&B encompasses many styles including hip hop, neo-soul and contemporary R&B.