Acupuncture is a traditional Chinese medical technique for unblocking chi (ch'i or qi) by inserting needles at particular points on the body to balance the opposing forces of yin and yang. Chi is an energy that allegedly permeates all things. It is believed to flow through the body along 14 main pathways called meridians.
When yin and yang are in harmony, chi flows freely within the body and a person is healthy. When a person is sick, diseased, or injured, there is an obstruction of chi along one of the meridians. Traditional Chinese medicine has identified some 500 specific points where needles are to be inserted for specific effects.