It involves stimulating sensory nerves under the skin and in the muscles of the body. This results in the body producing natural substances, such as pain-relieving endorphins. It's likely that these naturally released substances are responsible for the beneficial effects experienced with acupuncture.
A course of acupuncture usually creates longer lasting pain relief than when a single treatment is used.
Traditional acupuncture is based on the belief that an energy, or "life force", flows through the body in channels called meridians. This life force is known as Qi (pronounced "chee").
Practitioners who adhere to traditional beliefs about acupuncture believe that when Qi doesn't flow freely through the body, this can cause illness. They also believe acupuncture can restore the flow of Qi, and so restore health.