Dementors are guards of Azkaban(Wizard Prison) they feed on all Happy thoughts and feelings they will suck out your soul if they perform the kiss which is when they place their mouth on a wizard or muggles mouth then all your happy memories, thoughts and
feelings and your soul so you are left with nothing but the worst memories of your life!!
Dementors are hooded creatures with Grey skin covered in Scabs. They have no eyes they sense people through thoughts, memories and feelings.