Acupuncture is a many millennia-old method of accessing the functional effects of the acupoint meridian network of the human body. Part of the same family of medicine as acupressure and Shiatsu massage, Acupuncture inputs new information into the body-mind system and can create both incredibly specific changes to musculature, the brain, and organs as well as broad stimulation of the relaxation pathways of the brain, a homeostatic effect on the immune system, and powerful effects on the endocrine (hormonal) system.

By using fine hairlike filaments to stimulate these points, it creates minute impressions which continue activating these points for long after each session. Acupuncture can also be used for direct muscle stimulation and to stimulate trigger points to eliminate pain and inflammation and reset muscle tone. 

There have been over 14,000 clinical trials of acupuncture, according to the Cochrane Review (in comparison, there have been 12,000+ for physical therapy and 1000+ for chiropractic). To look up research easily, here is a link to the NIH PubMed database of clinical trials and metanalyses.

Licensed Acupuncturists (L.Ac.) in Colorado are required to have either a Master's Degree or a Doctorate in acupuncture and/or oriental medicine, and have a minimum of 2500 hours of post-graduate training.