The chakras from the Indian Yoga system are energy centers that represent the spectral differentiation of light as it emanates in the human body. When white light hits our atmosphere, it differentiates like this:
and then we have the chakras which take on the various colors from crown to root chakra like this:
From red to violet, the chakras are centers where the white light of awareness and consciousness expresses differently through the human psyche. Each of these wheels of light needs to spin in a healthy fashion as the state of our health and vitality depend on them. In the Indian yoga system, specific work is done to open, clear, and harmonize the flow and energy and light through these centers. It is a well articulated and well understood system of medicine, meditation, and enlightenment training. Understanding the dynamics of the chakras helps the practitioner understand themselves.
In the Chinese system of Qi Gong, we have a slightly different way we look at these centers. The basic premise is the same but the Qi Gong system simplifies it slightly by emphasizing three main reservoir areas called the dantiens. A dantien is an area in your energy field where the power is focused and concentrated. The dantiens look like this:
Here, the Qi Gong practitioner focuses his/her breath and attention to these various centers and, like the yoga system, works to open the energy flow, harmonize, and consolidate power in these various areas.
Both of these systems lead to the cultivation of the Light Body. The Light Body is the energetic force field around the human body that shows when the obstructions to qi or prana energy are removed by the practitioner. To cultivate the Light Body, one must remove impedance from the flow of the energy field by opening up the meridians (Chinese) or nadi (Indian) which are the energy pathways of the body. Meditation can also really help this. With these open, we open and cultivate the chakras or dantiens in order to allow the Universal Light to freely flow through us- making us a clear channel for its intelligence and activating our Light Body.