What attracts Moth's (and other winged bugs) to porch lights or any light source for that matter?

My windows are open in the house and in flew a Moth. He is above me as I type, flying in to the white globe light above my kitchen table. I tried to help it out however he seems content just flying in to the light over and over again and then resting and then repeating said activity. Why? What causes this?
I want to hear your ideas please limit google links and the scientific searches out of this thread we will leave that for the General Section.