and why is it necessary?

Ummm....well you put it on a cotton swab and dab it over your eye make up. It's important because unless you want to look like you've been on a 3 week drinking binge when you wake up, you need to remove your eye make up. Especially if you
have black eyeliner on and mascara.

You also need to wash your foundation and face make up off at night with a good cleanser, all the make up in the world can't help you look beautiful if you don't have a good base to work with...so keep your skin healthy.

it removes the makeup and dirt off your face. its necessary because makeup will give you acne, and damage your skin. i recommend the make-up remover from sephora , it was really cheap (about $7? i cant remember) but it works really well. just use it with a cotton swab or something and apply to your face. =)