Hertz
Named after Heinrich Hertz and abbreviated as Hz or illustrated as the f symbol, hertz equals one (0.00000000125) cycle per second, measuring the waves or frequencies of electric changes each second. Hertz is commonly used to measure a computer monitor's refresh rate and in computer processors. In the below picture of a wave, one oscillation is a representation of a cycle or hertz. You can think of an oscillation as a top and bottom of an oval, if you were to take the bottom half of the wave and put it directly below the top half it would make a complete oval.
Also see: Cycle, Frequency, Measurement, Power definitions, Processor definitions, Wave