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).