Self-harm, is defined as the intentional, direct injuring of body tissue, done without the intent to commit suicide.  Other terms such as cutting and self-mutilation have been used for any self-harming behaviour regardless of suicidal intent.   The most common form of self-harm is using a sharp object to cut one’s skin.  Other forms include behaviour such as burning, scratching, or hitting body parts. While older definitions included behaviour such as interfering with wound healing, excessive skin picking (dermatillomania), hair pulling (trichotillomania) and the ingestion of toxic substances or objects as self-harm, in current terminology those are differentiated from the term self-harm.

The desire to self-harm is a common symptom of some personality disorders.  People with other mental disorders may also self-harm, including those with depression, anxiety disorders, substance abuse, eating disorders, post-traumatic stress disorder, schizophrenia, and dissociative disorders.