From Wikipedia
Acupuncture is a collection of procedures involving penetration of the skin with needles to stimulate certain points on the body. In its classical form it is a characteristic component of traditional Chinese medicine (TCM).
It has been categorized as a complementary health approach. According to traditional Chinese medicine, stimulating specific acupuncture points corrects imbalances in the flow of qi through channels known as meridians.
Scientific investigation has not found any histological or physiological correlates for traditional Chinese concepts such as qi, meridians, and acupuncture points, and some contemporary practitioners use acupuncture without following the traditional Chinese approach…
Acupuncture’s use for certain conditions has been recognized by the United States National Institutes of Health, the National Health Service of the United Kingdom, the World Health Organization, and the National Center for Complementary and Alternative Medicine.