Kundalini (Sanskrit), literally "coiled". In Indian yoga, a "corporeal energy" -
Yoga and Tantra propose that this energy may be "awakened" by such means as austerities, breath and other physical exercises, visualization and chanting. It may then rise up a subtle channel at the spine (called Sushumna) to the head, bringing psychological illumination. Yogis tend to attempt this alone, Tantrics in couples, both usually under the instruction of a guru.
When Kundalini Shakti is conceived as a goddess, then, when it rises to the head, it unites itself with the Supreme Being (Lord Shiva). The aspirant becomes engrossed in deep meditation and infinite bliss.
According to Paramhans Swami Maheshwarananda awakening of kundalini shows itself as "awakening of inner knowledge". Like every form of energy one must also learn to understand spiritual energy. In order to be able to integrate this spiritual energy, careful purification and strengthening of the body and nervous system are required beforehand. By trying to force results considerable psychic disturbances and at times even permanent mental damage can occur. A spiritual master who walked this path before is required to guide the aspirant. Often will be found that negative experiences occurred only when acting without appropriate guidance or ignoring advice.