This document discusses the origins and development of R&B and its crossover into mainstream popularity in the 1950s, focusing on influential artists from New Orleans and the South such as Fats Domino, Little Richard, and Ray Charles. It also covers James Brown and his transition to crossover success in the 1960s, as well as Sam Cooke's move from gospel to popular music. Additionally, it discusses Chess Records in Chicago and their role in releasing early rock music, including influential artists Chuck Berry and Bo Diddley.