The term Hertz is used in place of “cycles per second” in honor of Heinrich Rudolf Hertz, who proved the existence of electromagnetic waves. It is commonly abbreviated as “Hz”.
The length of time required for one complete cycle of a waveform that repeats is referred to as the period. Thus repeating waveforms such as sine waves are referred to as “periodic.”
The unit of frequency of a periodic waveform is Hertz. The frequency is equal to 1/period or “the inverse of the period.” For example, one cycle of a 1,000 Hz sine wave has a period of 1/1000th of a second.