Back beat

Back beat is a style of percussion in common time where a strong rhythmic accent is sounded on the second and fourth beats of the bar, often from striking a snare drum.

The style emerged in the late 1940s in rhythm and blues recordings, and is one of the defining characteristics of rock and roll. Drummer Earl Palmer states the first record with nothing but back beat was "The Fat Man" by Fats Domino in 1949, which he played on. Palmer says he adopted it from the shout [last] chorus in Dixieland.