Psychotherapy (also psychological therapy, talk therapy, or talking therapy) is the use of psychological methods, particularly when based on regular personal interaction, to help a person change behavior, increase happiness, and overcome problems. Psychotherapy aims to improve an individual's well-being and mental health, to resolve or mitigate troublesome behaviors, beliefs, compulsions, thoughts, or emotions, and to improve relationships and social skills. Numerous types of psychotherapy have been designed either for individual adults, families, or children and adolescents. Certain types of psychotherapy are considered evidence-based for treating some diagnosed mental disorders; other types have been criticized as pseudoscience. There are hundreds of psychotherapy techniques, some being minor variations; others are based on very different conceptions of psychology. Most involve one-to-one sessions, between the client and therapist, but some are conducted with groups, including families. Psychotherapists may be mental health professionals such as psychiatrists, psychologists, mental health nurses, clinical social workers, marriage and family therapists, or professional counselors. Psychotherapists may also come from a variety of other backgrounds, and depending on the jurisdiction may be legally regulated, voluntarily regulated or unregulated (and the term itself may be protected or not). Definitions The term psychotherapy is derived from Ancient Greek psyche (ψυχή meaning "breath; spirit; soul") and therapeia (θεραπεία "healing; medical treatment"). The Oxford English Dictionary defines it as "The treatment of disorders of the mind or personality by psychological means...", however, in earlier use it denoted the treatment of disease through hypnotic suggestion. Psychotherapy is often dubbed as a "talking therapy" or "talk therapy", particularly for a general audience, though not all forms of psychotherapy rely on verbal communication. Children or adults who do not engage in verbal communication (or not in the usual way) are not excluded from psychotherapy; indeed some types are designed for such cases. The American Psychological Association adopted a resolution on the effectiveness of psychotherapy in 2012 based on a definition developed by American psychologist John C. Norcross: "Psychotherapy is the informed and intentional application of clinical methods and interpersonal stances derived from established psychological principles for the purpose of assisting people to modify their behaviors, cognitions, emotions, and/or other personal characteristics in directions that the participants deem desirable". Influential editions of a work by psychiatrist Jerome Frank defined psychotherapy as a healing relationship using socially authorized methods in a series of contacts primarily involving words, acts and rituals—which Frank regarded as forms of persuasion and rhetoric.