Refresh Rate of a Monitor:

This is the speed at which the monitor's picture is redrawn or flashed in front of your eyes. Slower refresh rates provide a noticeable flicker. Higher refresh rates create a steady picture (and is easier on your eyes). The refresh rate is determined by the video card, but also must be supported by the monitor. The maximum refresh rate will be different for different resolutions. A minimum of 75 Hertz is recommended (TV refresh rates are 30 Hz, which is why there is a noticeable flicker).