What is a flicker effect?

What is a flicker effect, flicker effect is rapid, repeated change in brightness or visibility of light source or image that appears to flash on and off quickly, creating unsteady, wavering, or fluttering visual impression that can be distracting or cause discomfort. In lighting, flicker effect is when light bulb flickers due to voltage fluctuation, loose wiring, or failing ballast, causing light to go bright dim quickly. In video and film, flicker effect is visual artifact where brightness fluctuates between frames, often caused by mismatched frame rate and artificial lighting frequency, like fluorescent lights flickering on camera. In psychology, flicker effect can cause eye strain, headache, and in photosensitive epilepsy, flickering lights can trigger seizures. In special effects, flicker effect is deliberately created to simulate candlelight, fire, old film, or lightning, using rapid brightness changes for dramatic effect. In monitors, flicker effect is when screen refresh rate low causing visible flicker that strains eyes. So flicker effect is rapid variation in light intensity causing perceptible flashing or wavering, whether unwanted artifact from electrical or technical issues or intentional effect for artistic purposes, with flicker measured as percent modulation of light intensity over time.