The frequency with which a raster beam repeats the scan of a computer monitor (or other cathode-ray tube), or the number of times per second the screen redraws itself. The faster the refresh rate of a monitor, the less of a discernible flicker it will have. Generally speaking, a refresh rate of at least 70 Hertz (Hz)—or, in other words, 70 screen redraws per second—is the minimum for flicker-free monitors. Depending on the monitor's brightness setting and the lighting of the room it is in, however, even somewhat higher refresh rates can generate a flicker. By the way, it is the difference in the scan rate of a computer monitor and a television screen that causes the visibility of the raster line when a computer display is shown on TV.