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 a computer processor's speed. In the picture below of a wave, one oscillation is a representation of a cycle or hertz. You can think of an oscillation like the top and bottom of an oval. If you take the bottom half of the wave and put it directly below the top half, it makes a complete oval.