Neuro-linguistic programming (NLP) was developed in the 1970s by Richard Bandler and John Grinder at the University of California, Santa Cruz. Their starting idea was to study effective therapists — originally Fritz Perls, Virginia Satir and Milton Erickson — closely enough to extract the specific language patterns and techniques that made them effective, and teach those patterns directly.
NLP is best described as a toolbox of communication and self-observation techniques rather than a single method: reframing a problem in different language, "anchoring" a state to a physical gesture, rehearsing a difficult conversation in the mind before having it, and paying close attention to a person's own words when they describe a goal or a fear. In the healing context of this site, it is generally used as a self-help tool for changing habitual thought patterns — the mental side of the same idea that appears elsewhere here as diet, breath or posture.
NLP has been studied more than most alternative approaches, and the picture is mixed. Several of its founding technical claims — such as eye-movement patterns reliably indicating whether someone is visualising, recalling sound, or lying — have not held up under controlled testing. At the same time, some of its component techniques overlap with tools used in mainstream cognitive behavioural therapy, such as reframing and mental rehearsal, which do have supporting evidence in their own right. Treat NLP as a set of communication techniques to try, not as a validated therapy for diagnosed mental health conditions — for those, a qualified psychologist or psychiatrist remains the right first call.