system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How do night vision goggles work?
gpt
There are several ways:

* Infrared: There are electronics that can see "color" lower than red. As things and beings radiate those colors as heat, you can use it to see in the dark. Also, as infrared is invisible to the human eye those night vision devices can be enhanced with a "infrared flashlight". It works like with normal light, just in an invisible part of the spectrum that then is shown to you in a visible one. Heat vision and "infrared just below the red" are actually two different beasts, but for this scope here saying "light below your visibility" is sufficeient. 

* Enhancement of the existing light. For example electronics that are more sensible than your eyes and that light is then enhanced. But what you usually mean is expalined by mainman879, photons hit a place in a vacuum tube, those cause a shower of electrons which fall on a plate that gets flourescent in those places and that you can see.