system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why is it that normal pencils will rub off with an eraser, but color pencils won't?
gpt
Color pencil pigment is carried by wax, which only smears around when it's written on something and then erased. You're essentially writing with a form of grease that carries a coloring agent, and like rubbing your finger across a greasy frying pan, doesn't remove it that well without some other form of chemical help (which would likely destroy the paper it's written on in the process).

Pencil leads are made largely from graphite, a naturally black carbon form that transfers very well to paper in a tacky powder of sorts. Because it doesn't require any sort of glue to stay in place, and because it doesn't need any sort of wax to carry a different pigment (which is composed of different molecules for different colours), you only really need pressed graphite in the lead. 

Tacky rubber or plastic erasers remove graphite from paper very well because that substance sticks to graphite better than paper does, so it lifts it off and removes it in the little flakes that come away from your eraser as you use it up.