The Sl unit of frequency
In recognition of the importance of Hertz’s researches into electromagnetic waves, his name has been given to the unit of frequency. The SI unit of frequency is called the hertz (Hz) and is equal to a frequency of 1 cycle per second.
The term hertz is not restricted to wave frequencies only but is used for any regularly occurring event, e.g., the frequency of a pendulum, an alternating current, a musical note, and so on. Larger frequency units in common use are