Flicker (screen) - Definition and Overview

Flicker is visible fading between image frames displayed on cathode ray tube (CRT) based monitor. Flicker occurs when the monitor's CRT is driven at a low refresh rate, allowing the screen's phosphors to lose their excitation between sweeps of the electron gun. For example, if a computer monitor's vertical refresh rate is set to 60 Hz, most monitors will produce a visible "flickering" effect. Most people find that refresh rates of 85 Hz and above enable flicker-free viewing on CRTs. Refresh rates above 120 Hz are uncommon, as they provide no noticeable flicker reduction. On LCD displays, lower refresh rates (around 75 Hz) are often acceptable.

Flickering also occurs in the cinema as the film is projected as 24 still images each second.