Psychiatry is the medical specialty devoted to the study, diagnosis, treatment, and prevention of mental disorders. These include various affective, behavioural, cognitive and perceptual abnormalities.

Initial psychiatric assessment of a person typically begins with a case history and mental status examination. Psychological tests and physical examinations may be conducted, including on occasion the use of neuroimaging or other neurophysiological techniques. Mental disorders are often diagnosed in accordance with criteria listed in diagnostic manuals such as the widely used Diagnostic and Statistical Manual of Mental Disorders (DSM), published by the American Psychiatric Association, and the International Classification of Diseases (ICD), edited and used by the World Health Organization. The fifth edition of the DSM (DSM-5) was published in 2013, and its development was expected to be of significant interest to many medical fields.

The combined treatment of psychiatric medication and psychotherapy has become the most common mode of psychiatric treatment in current practice, but current practice also includes widely ranging variety of other modalities. 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. Research and treatment within psychiatry, as a whole, are conducted on an interdisciplinary basis, sourcing an array of sub-specialties and theoretical approaches.

A mental disorder, also called a mental illness, psychological disorder or psychiatric disorder, is mental or behavioral pattern that causes either suffering or a poor ability to function in ordinary life. Many disorders are described. Conditions that are excluded include social norms. Signs and symptoms depend on the specific disorder.

The causes of mental disorders are often unclear. Theories may incorporate findings from a range of fields. Mental disorders are usually defined by a combination of how a person feels, acts, thinks or perceives.[1] This may be associated with particular regions or functions of the brain, often in a social context. A mental disorder is one aspect of mental health. The scientific study of mental disorders is called psychopathology.

Services are based in psychiatric hospitals or in the community, and assessments are carried out by psychiatrists, clinical psychologists and clinical social workers, using various methods but often relying on observation and questioning. Treatments are provided by various mental health professionals. Psychotherapy and psychiatric medication are two major treatment options. Other treatments include social interventions, peer support and self-help. In a minority of cases there might be involuntary detention or treatment. Prevention programs have been shown to reduce depression