A simple style of folk music heard mostly in the southern United States; usually played on stringed instruments (Wordnetweb/Princeton University).
Country music (or country and western) is a blend of traditional and popular musical forms traditionally found in the Southern United States and the Canadian Maritimes that evolved rapidly beginning in the 1920's. Distinctive variations of the genre have also emerged elsewhere including Australian country music.
The term country music gained popularity in the 1940s when the earlier term hillbilly music came to be seen as denigrating. Country music was widely embraced in the 1970s, while country and Western has declined in use since that time, except in the United Kingdom and Ireland, where it is still commonly used. However, in the Southwestern United States a different mix of ethnic groups created the music that became the Western music of the term country and Western. The term country music is used today to describe many styles and subgenres.
Country music has produced two of the top selling solo artists of all time. Elvis Presley, who was known early on as "the Hillbilly Cat" and was a regular on the radio program Louisiana Hayride, went on to become a defining figure in the emergence of rock and roll. With 129.5 million albums sold, Presley is the top-domestic-selling solo artist in U.S. history.Contemporary musician Garth Brooks, with 128 million albums sold, is the second best-selling solo artist in U.S. history.
While album sales of most musical genres have declined since about 2005, country music experienced one of its best years in 2006, when, during the first six months, U.S. sales of country albums increased by 17.7 percent to 36 million. Moreover, country music listening nationwide has remained steady for almost a decade, reaching 77.3 million adults every week, according to the radio-ratings agency Arbitron, Inc., (Wikipedia).
Southern rock is a subgenre of rock music, and genre of Americana. It developed in the Southern United States from rock and roll, country music, and blues, and is focused generally on electric guitar and vocals (Wikipedia).
Country rock is sub-genre of popular music, formed from the fusion of rock with country. The term is generally used to refer to the wave of rock musicians who began to record country-flavored records in the late 1960s and early 1970s, beginning with Bob Dylan and The Byrds; reaching its greatest popularity in the 1970s with artists like Emmylou Harris, the Eagles and Pure Prairie League (Wikipedia).