system
Given the following post, respond as if you're commenting on Reddit:
human
Eli5: Why do so many monitors and screens work at either 30, 60, 120, or 144 hertz, rather than for example 50 or 100 hz?
gpt
In USA they chose 60Hz as AC frequency. Because old CRT monitors where using that current directly (or divisors). 24 frames per seconds is easy to align on that frequency and became the standard in USA.

Funny enough, once color TV came in, the standard had to squeeze a little bit more data, and they shifted the frequency to 59.94 Hz to give that extra time, and NTSC was born.

Because of this, most monitor work with multiples of 60 or 24.

In Europe they had a PAL format based on 50Hz. For which 25 frames per second was easier to match, so it became standard over there.

Now modern panels can do any frequency refresh they want, the only reason to limit to those frequencies is because we want to. It's just software that abide to old standard.

I wish we would get rid of the 59.94 and round it to 60, so that we can leave the past behind. As for multiple of 50, let us wait for 300Hz monitor and forget about the distinction.