system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: What is the benefit of blueprints being white over blue?
gpt
Back in the day, there used to be a process where you would pen a half-transluscent blue paper and whith a light you could reproduce it accuratly to another paper, kind of like photography film.

Now blueprints are rarely blue, they are printed on a plotter (printer) and are usually black on white.  If they are blue, its for style.  

Personally i hate black on white because in the sunlight, on a hood of a car, i find it easier to read a white on dark piece of paper, as opposed to black on white.