system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why are fluorescent colors special and why did they not seem to exist before the 80's?
gpt
Other people have addressed your comment about the timeframe. 

Here's why they are special:
Normal colors reflect the color you see and absorb anything else (a blue shirt absorbs red, yellow, green, etc. but reflects blue). This means that if there light hitting the shirt has 100 brightness units, the shirt can reflect up to 100 brightness units back.

Fluorescent colors are able to absorb energy from beyond the range we can see (UV) and then re-emit it in a color we can see. So a fluorescent blue shirt could reflect up to 100 brightness units back of blue, and absorb another 100 brightness units of UV and emit them back as blue light, giving off 200 brightness units of blue in a room where everything else is only giving off 100.