An increasing number of adolescents, particularly females, secretly cut, scratch or burn their skin in an attempt to feel better. They damage their skin purposely and voluntarily as a way to cope with overwhelming emotions they simply cannot verbalize. This behavior is referred to as cutting, which falls under the larger umbrella of self-injury or self-harm, and has also been called self-mutilation. Although these adolescents are causing bodily harm to themselves, they typically do not want to die.
Self-injury is shocking and confusing to outside observers. Parents who discover their child is repeatedly and deliberately hurting his or her own body are usually alarmed and frightened. Most adolescents attempt to hide their behavior from their family members and parents are often completely unaware of it, even when the teen is doing it at home - in the very home they share.
http://www.thefamilyschool.com/index.php?src=gendocs&ref=Self Injury&category=Resources for Parents