Hertz

The SI unit hertz, abbreviated as Hz, expresses frequency in terms of oscillations per second (s^-1, 1/s). For example, red light has a frequency of about 4.6×10¹⁴ Hz. The unit has been assigned the name "hertz" to honor the German physicist Heinrich Rudolf Hertz who made some important contributions to science in the field of electromagnetism.

1 kHz = 1,000 Hz
1 MHz = 1,000,000 Hz

In older writings, the term cycle per second (cps) is seen.