system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why can't we have smaller pixels? Why are pixels used?

EDIT: thanks for all the great answers, guys!
gpt
Smaller pixels than what? We do have small pixels, and they get smaller depending on the device.

Look at the iPad 2 versus the "new" iPad (3rd or 4th generation). Both have the same sized screen, but the new iPad has 4 times as many pixels per inch.