Visual flicker refers to the rapid and repeated changes in brightness or color of a visual stimulus, which can occur in various settings, such as screens or lighting. This phenomenon can be caused by fluctuations in power supply, refresh rates of displays, or the way light sources operate. Exposure to visual flicker can lead to discomfort, eye strain, or headaches for some individuals. It is particularly relevant in discussions about the effects of LED lighting and computer screens on visual health, as prolonged exposure may exacerbate symptoms in sensitive individuals.