What part of the head do you use for a head butt?

Your forehead is used for a 'head butt'. However, it is important to say that 'head butting' can cause considerable injury! It can cause a broken nose, skull fracture, concussion, brain injury, or even sudden death (also known as a "one punch death"). Head butting should be left to animals who use it to communicate authority and alpha status, as well as a 'greeting', since animals rarely break each others skulls or cause injury or death!

Again, 'head butting' is a form of immature aggression in humans and can cause considerable injury or death! NO ONE should head butt another person!