In Yoga philosophy the seven chakras are powerful energy centers within the body which represent different levels of consciousness. The meaning of chakra is "wheel", a vortex of light, vibration and energy. They are located within the astral (subtle body of light) spine, inside the physical body. The first or root chakra is found at the bottom of the spine; next are the sacral, navel, heart, throat, third eye, or ajna, and at the top of the head, the crown or 1,000 petaled lotus, chakra

The kundalini is the energy at the base of the spine, often thought of as the "sleeping serpent", because it "sleeps" until spiritually awakened by the soul occupant of the body. The movement of the kundalini, first awakening, and then moving through the astral spine through the various chakras and up to the 7th chakra, or crown chakra, is the process of spiritual enlightenment. The entire spiritual process of a human being from the first incarnation to the last, takes place in the 4 feet or so beginning at the spinal root and ending at the top of the head. For those who are interested in personal growth, evolution, or spiritual enlightenment, having a clear understanding of the role of the inner energies and the chakras is extremely helpful.

More Info: yogava.com