Diagnostic and Statistical Manual of Mental Disorders (DSM)
DSM is a Diagnostic and Statistical Manual of Mental Disorders, published by the American Psychiatric Association. It is the method used to classify and diagnose mental disorders in the United States.
In 1952 when it was first published the DSM only contained 66 disorders, in 1968 the disorders listed in the manual grew to over 100 hundred along with its second edition.
The third edition came in 1979 which in it was introduced an Axis system of 5 scales.
Example: A mental illness might fall under Axis I
Axis I - Clinical Disorders
Axis II - Personality Disorders & Mental Retardation
Axis III - General Medical Conditions
Axis IV - Psychosocial & Environmental Problems (stressors)
Axis V - Global Assessment of Functioning