The description is actually not very good. Input lag doesn't purely exist because of liquid movement and pixels changing colors. If it would, then an input lag

The description is actually not very good. Input lag doesn't purely exist because of liquid movement and pixels changing colors. If it would, then an input lag of 50-100ms (which where common with older generation LCDs) - would also mean the screens response time (the time to change color) would be that high. Which would mean your picture would be a blurry mess. The majority of input lag came from additional signal processing algorithms which were built into LCDs, which buffered the full picture for 1-2 frames. E.g. to apply overdrive algorithms, color correction, scaling, etc. Those are all running before the signal gets towards the crystals. I think a lot of that was actually just bad design in the earlier generation of LCDs. And it was really bad, I had a screen with 100ms input lag and neither working nor gaming on it was really fun. But it seems like manufacturers now understand the problem better and try to minimize the delay through signal processing.