in the united kindom and united states
To me the most important instrument in rock music is the electric guitar.
Obviously, Rock music since most of her Songs are Rock songs!
Usually rock, country, metal, pop, blues, etc. mostly because those are the kinds that win the music recording sales certificates, the three albums sold the most were: Michael Jackson's "thriller" (sold 29 million copies), the eagles's greatest hits (sold 29 milions copies as well), and pink Floyd's "the wall" (sold 23 million copies), and those are pop and rock.
Typical meter for rock music is in 4/4 meter.
Kiss
Country music, pop, and rock
let it be
1979-1986 are the years rock was most popular
Rock music was developed in the 60's and most people who listen to Rock Music where teenagers or young adults during that time.
Wikipedia has a "List of best-selling music artists" (http://en.wikipedia.org/wiki/List_of_best-selling_music_artists). It shows that the BEATLES are at the top of the list, and it does show them for the "Rock / Pop rock" category.
the beatles
Garth Brooks