In TCM, the body has what are commonly called meridians or channels. Energy and Qi are thought to flow along the meridians.
There are 12 Standard Meridians. These are channels connecting a primary organ (or body function) to the surface of the body, and through branch channels secondarily to other organs.
Where the meridian runs along the surface of the body, we get key points, sometimes called acupuncture or acupressure points. By working on the acupuncture points on the meridian that is linked to a specific organ, we can actually have an effect on that organ. In this way the surface of the body, on top of the skin, can actually impact organs deep inside the body. This is the way acupuncture, acupressure, and in some cases, tuina works. Therefore to understand and properly use acupuncture, a knowledge of meridians and their associated points is essential.