The online information service, Wikipedia, describes art therapy as follows ... Because of its dual origins in art and psychotherapy, art therapy definitions vary. It can either focus on dealing with the art-making process as therapeutic in and of itself ("art as therapy"), or on the psychotherapeutic transference process between the therapist and the client who makes art. The therapist interprets the client's symbolic self-expression, as communicated in the art, and elicits interpretations from the client.”
Art therapy finds good use in prisons and institutions caring for disturbed individuals. The ability to express oneself in a painting or drawing can engender a sense of freedom and having some control over life.
In these ways it can be therapeutic and empowering.