PWM dimming
Also called PWM flicker · pulse width modulation
PWM dimming lowers a screen’s brightness by switching the light on and off very rapidly instead of reducing it steadily. Some people see it as flicker or get eye strain from it, mostly at low brightness settings.
In practice
Many screens dim by switching the light on and off hundreds or thousands of times a second. The flicker is too fast to see directly but some people get headaches or eye strain from it, especially at low brightness where the off periods are longest. Higher frequency dimming and DC dimming reduce or remove the effect.
How to check
A browser can’t measure PWM. One rough check is to point a phone camera at the screen at low brightness and look for dark bands rolling across the image. Reviews that measure flicker are more reliable. If you are sensitive to it, raise the screen brightness and lower the room brightness instead.