Electronic circuits are not musical by nature, although many fabulous things are done nowadays with digital synthesizers, but there needs to be a conductor that establishes a beat. A special device called a clock generates a series of pulses which are used like the beats of a conductor. Other circuits change their state by synchronizing with the pulses coming out of the clock. (To synchronize means "to come together in time," and means in general to coordinate two or more actions so that they happen at the same time.)