Rock N Roll can trace its roots from a mixture of Rhythm and Blues and Country music from the southern United States in the early twentieth century. In the 1940s and 1950s, the two genres combined into the earliest forms of Rock, such as Doo Wop, Rockabilly and Surf Rock.
Early American artists such as Elvis Presley and Chuck Berry eventually influenced European acts such as the Beatles and the Rolling Stones that rejuvenated the genre in the 1960s.
An earlier schism between mainstream and underground influences in American musical culture that combined into Rock N Roll began to reemerge by the early 1970s. The decade saw mainstream sub-genres such as Pop and Disco, as well as more underground styles such as Punk and Heavy Metal, gain popularity among audiences.
The 1980s marked more maturity in the genre's development with the introduction of the pop influenced New Wave genre and R&B influenced pop singers such as Michael Jackson.
In the early 1990s, underground Rock genres returned to the forefront under the banner of "Alternative music." Alternative sub-genres such as Emo, Grunge, Hardcore, Ska and numerous others renewed the underground while eventually merging with mainstream styles once again to create the wide variety we find in Rock today.