Genre of popular music that originated within African-American communities in the 1940s
Rhythm and blues, frequently abbreviated as R&B or R'n'B, is a genre of popular music that originated in African-American communities in the 1940s. The term was originally used by record companies to describe recordings marketed predominantly to urban African Americans, at a time when "urbane, rocking, jazz based music with a heavy, insistent beat" was becoming more popular. Wikipedia