Refresh rate
How many times per second the display redraws its image, measured in hertz. 60 Hz is the floor, 120–144 Hz is common today, 240–540 Hz exists for esports.
Constantly confused with FPS: frame rate is how many images the computer produces, refresh rate how many the display shows. When the two are unsynchronized you get tearing (half old frame, half new) or stutter. The fix is variable refresh rate — G-Sync and FreeSync — where the display waits for the GPU instead of the other way around. Refresh rate also sets the floor for input latency: at 60 Hz an image can be up to 16.7 ms old. Motion blur additionally depends on panel response time, which is why OLED looks sharper than LCD at the same hertz.