system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why do you have to "charge" glow in the dark stuff?

You know how you have to hold glow in the dark items under light to "activate" them?  The only answer my drunken, man-child brain can muster is that it traps the light and holds for later use.  I'm also pretty sure that is incorrect.
gpt
That's actually pretty much correct.

It is called "phosphorescence" and basically means that it doesn't re-emit the light that it absorbs immediately (the way light shining on a red object would just absorb and then reflect back red light immediately at the same strength as the light that hit it, since it is all at once).

Phosphorescent materials absorb the light and then release it *slowly* over time by releasing it with lowered intensity.

That's why glow-in-the-dark items won't glow as bright as the light that was shining on them originally, but they can last longer.