American popular music had a great effect on music across the world. It appeared early in the 19th century, and in the 20th century the American music industry developed a series of new forms of music, using blues and other elements of American folk music. These popular styles included country, R&B, jazz and rock. The 1960s and '70s saw a number of important changes in American popular music, including the development of a number of new styles, such as heavy metal, punk, soul, and hip hop. Though these styles were not popular in the sense of mainstream, they were commercially recorded and are thus examples of popular music.
