Topic summary
On-beat
Extracted from the Wikipedia article Beat (music).
On-beat and off-beat
In typical Western music
4 time, counted as "1 2 3 4, 1 2 3 4...", the first beat of the bar (downbeat) is usually the strongest accent in the melody and the likeliest place for a chord change, the third is the next strongest: these are "on" beats. The second and fourth are weaker—the "off-beats". Subdivisions (like eighth notes) that fall between the pulse beats are even weaker and these, if used frequently in a rhythm, can also make it "off-beat".