system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How does night vision work, and why is it green?
gpt
Different models work in different ways. 

A typical 1980s-2000s night vision monacle will amplify all of the light that goes into it. It's essentially just a camera and a screen. 

They're green for various reasons. The human eye is slightly better at differentiating between different shades of green than it is with red and blue, so less light is required from the scope, reducing the chance that the light will "spill" and indicate the position of the observer. A side benefit about the low level of light is that it doesn't intefere with the shooters natural night-sight as much as brighter white light would.