Psychiatry is a medical speciality whose primary goal is the treatment of mental illness. Its name derives from the Greek for "healer of the mind". In the United States, it is practised by people holding M.D. or D.O. degrees.
While all clinicians encounter patients with mental illnesses and any of them may treat it, psychiatrists specialize in these areas. They are specifically trained in the differential diagnosis (the distinguishing of various forms) and treatment of mental illness. Treatment can involve medication, psychotherapy (such as cognitive behaviour therapy, interpersonal therapy, and psychodynamic psychotherapy), and psychosocial interventions.