Acupuncture is a form of alternative medicine in which thin needles are inserted into the body. It is a key component of traditional Chinese medicine (TCM). TCM theory and practice are not based upon scientific knowledge, and acupuncture is a pseudoscience（针灸是一门伪科学）. There is a diverse range of acupuncture theories based on different philosophies, and techniques vary depending on the country. The method used in TCM is likely the most widespread in the US. It is most often used for pain relief, though it is also used for a wide range of other conditions. Acupuncture is generally used only in combination with other forms of treatment.