Pop music is a term that from the late 1950s has been applied to the central and most widely circulated kinds of popular music, such as rock and roll and its related forms. Pop music originated in the United States in the 1920s from a family of folk music styles including blues and country that went on to form the basis of rock and roll and its subsequent forms. While pop and rock are related, or even, in some definitions, put together under the same heading, rock critics since the 1960s have tended to depict pop and rock as opposites; rock critics tend to consider rock as "serious" and "authentic" and call pop music "light" and "commercial".