What is it like to be colorblind?

on little miss sunshine, don't you think thye son would've known he was colorblind already?What is it like to be colorblind?
i didn't know till i was an adult
i see some color..but many look the same
How could a colorblind person possibly know they are colorblind? All they know is what they've seen.
i dont think people know they are colorblind until they are told. My dads best friend is color blind and had to be told what color his cars were. he says green and reds are the hardest to pic out. like on stop lights. its just a gray light on. I think we are told what color is what and if you are told since you were born that the blue pen you write with is actually purple all the time, would you grow up thinking its purple even though it says blue? I always thought its what we are told to think.