How do you explain color to someone who has been blind all their life?

Answer

If the person has been blind all of their life, explaining color to them would be impossible. How can anyone have a conception of what color even means, if they never had the experience of seeing anything except darkness?

That's right

A person who has never ever been sighted also has no concept of darkness, since darkness is a visual experience. This can be a difficult concept for a sighted person to get.