The Frequency is the rate at which a periodic event occurs. In electricity it is the rate at which current reverses direction in an alternating current system. In the US and some other countries, alternating current systems use a frequency of 60 cycles per second (60 Hz); in Europe and remaining countries, the standard is 50 Hz.
See also:
"Frequency" is in the UNSPSC Code "39121007"
Frequency converters