What is Entrainment?

In the study of chronobiology, entrainment occurs when rhythmic physiological or behavioral events match their period to that of an environmental oscillation. It is ultimately the interaction between circadian rhythms and the environment. A central example is the entrainment of circadian rhythms to the daily light–dark cycle.

An example of this would be HUYGEN'S observation of the pendulum clocks swaying in concerts. Any two oscillators of similar rhythms pulsating in close proximity will tend to pulse in harmony, so that their pulsations become synchronous.