Acupuncture is an ancient and continuously practiced form of Traditional Chinese  Medicine.

​Traditional Chinese Medicine describes an energy flow (Qi) that travels within our bodies through the 12 regular channels, also known as the Meridians, and each channel is connected to it's own organ. ​When these channels are blocked pain and diseases may occur. ​The blockages may be cleared through needle stimulation (acupuncture) or finger pressure (acupressure) on the acupuncture points (acupoints) which are located on the meridians. 
In acupuncture, small, solid, hair-thin needles are used to stimulate the acupoints and the central and peripherial​ nervous systems.​ Unlike medication, acupuncture​ repairs the internal organs in order to heal the body and helps prevent further problems in the future.

This is old chinese medicine theory about Acupuncture. If you want to know it by Qu​antum level,  Vibrational Medicinis one of the best book