Psychiatry is the medical specialty devoted to the diagnosis, prevention, and treatment of mental disorders.  These include various maladaptations related to mood, behaviour, cognition, and perceptions. See glossary of psychiatry.

The combined treatment of psychiatric medication and psychotherapy has become the most common mode of psychiatric treatment in current practice,  but contemporary practice also includes a wide variety of other modalities, e.g., assertive community treatment, community reinforcement, and supported employment. Treatment may be delivered on an inpatient or outpatient basis, depending on the severity of functional impairment or on other aspects of the disorder in question. An inpatient may be treated in a psychiatric hospital. Research and treatment within psychiatry as a whole are conducted on an interdisciplinary basis with other professionals, such as epidemiologists, nurses, or psychologists.

Psychiatry refers to a field of medicine focused specifically on the mind, aiming to study, prevent, and treat mental disorders in humans. It has been described as an intermediary between the world from a social context and the world from the perspective of those who are mentally ill.

People who specialize in psychiatry often differ from most other mental health professionals and physicians in that they must be familiar with both the social and biological sciences. The discipline studies the operations of different organs and body systems as classified by the patient's subjective experiences and the objective physiology of the patient.  Psychiatry treats mental disorders, which are conventionally divided into three very general categories: mental illnesses, severe learning disabilities, and personality disorders. While the focus of psychiatry has changed little over time, the diagnostic and treatment processes have evolved dramatically and continue to do so. Since the late 20th century, the field of psychiatry has continued to become more biological and less conceptually isolated from other medical fields.