Polyrhythm
also called “three against two”also called “cross rhythm”
The short version
Two different rhythms running at the same time and not lining up.
The classic is 3 against 2: one part fits three even hits in the same space another fits two. They only meet again at the start.
Why you'd careIt makes simple material sound complex and hypnotic — used constantly in West African music, jazz and math rock.
Go deeper
A polymeter is different: same note speed, different bar lengths (a 7-step loop against a 4-step loop), so the pattern shifts every bar before eventually resyncing.
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