The classical Chinese explanation is that channels of energy run in regular patterns through the body and over its surface. These channels, called meridians, are like rivers flowing through the body to irrigate and nourish the tissues, blood flow and nervous pulses also follow meridians to run through the body to various parts, structures and organs. An obstruction in the movement of these energy rivers are like a dam that backs up the flow in one part of the body and restricts it in others. Any obstruction and blockages or deficiencies of energy, blood and nervous pulses would eventually lead to disease.
Needling the acupuncture points can influence the meridians: the acupuncture needles unblock the obstruction at the dams, and reestablish the regular flow through the meridians. Acupuncture treatments can therefore help the body's internal organs to correct imbalances in their digestion, absorption, and energy production activities, and in the circulation of their energy through the meridians.
According to the needling methods, acupuncture can be divided into traditional acupuncture, ear acupuncture, electro-acupuncture, scalp acupuncture and hand acupuncture etc. Over the last few decades, traditional acupuncture was widely used combining with other techniques, like moxi-needling, cup-needling etc, to increase the therapeutic effects.
Modern science explain the functions of acupuncture as following: Needling the acupuncture points stimulates the nervous system to release chemicals in the muscles, spinal cord, and brain. These chemicals will either change the experience of pain, or they will trigger the release of other chemicals and hormones, which influence the body's own internal regulating system.
Acupuncture has been used by Chinese people for thousands of year, and it becomes more and more popular in the Western societies. Here is the BBC documentary film about the acupuncture.