Play therapy refers to a range of methods of capitalising on children's natural urge to explore and harnessing it to meet and respond to the developmental and later also their mental health needs. It is also used for forensic or psychological assessment purposes where the individual is too young or too traumatised to give a verbal account of adverse, abusive or potentially criminal circumstances in their life.

Play therapy is extensively acknowledged by specialists as an effective intervention in complementing children's personal and inter-personal development. Play and play therapy are generally employed with children aged six months through late adolescence and young adulthood. They provide a contained way for them to express their experiences and feelings through an imaginative self-expressive process in the context of a trusted relationship with the care giver or therapist. As children's and young people's experiences and knowledge are typically communicated through play, it is an essential vehicle for personality and social development.

In recent years, play therapists in the western hemisphere, as a body of health professionals, are usually members or affiliates of professional training institutions and tend to be subject to codes of ethical practice.

Jean Piaget emphasized play as an essential expression of children's feelings, especially because they do not know how to communicate their feelings with words. Play helps a child develop a sense of true self and a mastery over their innate abilities resulting in a sense of worth and aptitude. During play, children are driven to meet the essential need of exploring and affecting their environment. Play also contributes in the advancement of creative thinking. Play likewise provides a way for children to release strong emotions. During play, children may play out challenging life experiences by re-engineering them, thereby discharging emotional states, with the potential of integrating every experience back into stability and gaining a greater sense of mastery.

Play therapy is a form of psychotherapy which uses play as the main mode of communication especially with children, and people whose speech capacity may be compromised, to determine and overcome psychosocial challenges. It is aimed at helping patients towards better growth and development, social integration, decreased aggression, emotional modulation, social skill development, empathy, and trauma resolution. Play therapy also assists with sensorimotor development and coping skills.

Play therapy is an effective technique for therapy, regardless of age, gender, or nature of the problem. When children do not know how to communicate their problems, they act out. This may look like misbehavior in school, with friends or at home. Play therapy seeks to provide a way children can cope with difficult emotions and helps them find healthier solutions and coping mechanisms.

Play therapy can also be used as a tool for diagnosis. A play therapist observes a client playing with toys (play-houses, soft toys, dolls, etc.) to determine the cause of the disturbed behaviour. The objects and patterns of play, as well as the willingness to interact with the therapist, can be used to understand the underlying rationale for behaviour both inside and outside of therapy session. Caution, however, should be taken when using play therapy for assessment and/or diagnostic purposes.

According to the psychodynamic view, people (especially children) will engage in play behaviour to work through their interior anxieties. According to this viewpoint, play therapy can be used as a self-regulating mechanism, as long as children are allowed time for free play or unstructured play. However, some forms of therapy depart from non-directiveness in fantasy play, and introduce varying amounts of direction, during the therapy session.