Rock-n-roll music is 4/4 time with a backbeat (emphasis on the
off-beats, beats 2 and 4). While the same would also describe
other styles such as Ska and Hip-hop, these other styles all
have additional descriptors. The question "Is it rock-n-roll?"
is equivalent to "Is it in 4/4 time with a backbeat?". Rock-n-
roll developed from "Race" Music (now called Rhythm&Blues) in
the 1950s, and its typical tone and style reflects the
"rebellious" nature of its birth. Often the same songs were
recorded by black artists and white artists to be marketed to
different demographics.