Beat
The steady pulse of the music, the thing you tap your foot to.
Also: pulse, count
The beat is the regular pulse that runs under a piece of music. It is what an audience claps along with and what dancers count. Most dance teaching is done in counts of the beat, often in groups of eight. Beats are not all equal. Some are felt as stronger than others, and the pattern of strong and weak beats gives the metre. A dancer who steps exactly with the pulse is said to be on the beat or in time.