Beats provide the basic unit of measurement for time in music; if ordinary clock time is measured in seconds, musical time is measured in beats. When listening to a marching band or a rock band, to take two clear examples, we sense a regular recurrence of short pulses. These serve as a steady, vigorous background for other, more complicated rhythms that we discern at the same time. Sometimes we can’t help beating time to the music, dancing to it, waving a hand or tapping a foot. The simple pulse being signaled by waving, tapping, or dancing is the music’s beat.

There is, however, an all-important difference between a clock ticking and a drum beating time. Mechanically produced ticks all sound exactly the same, but it is virtually impossible for people to beat time without making some beats more emphatic than others. This is called giving certain beats an accent. And accents are really what enable us to beat time, since the simplest way to do this is to alternate accented (“strong”) and unaccented (“weak”) beats in patterns such as ONE two ONE two ONE two . . . or ONE two three | ONE two three | ONE two three. . . . To beat time, then, is not only to measure time according to a regular pulse but also to organize it, at least into these simple two-and three-beat patterns.