In human beings, Shakti, the female aspect is called "Kundalini". This is the vital energy that rests at the base of the spinal cord. The Yoga Upanishads describe Kundalini as lying "coiled" at the base of the spine, represented as either a goddess or sleeping serpent waiting to be awakened. The object of Tantric practice of Kundalini Yoga is to awaken the cosmic energy and make it ascend through the psychic centers, the charkas that lie along the axis of the spine as consciousness potentials. The female Shakti then again unites above the crown of the head with Shiva, the pure consciousness. This union aims at Kundalini Yoga. Thus duality turns into unity and fusion with the absolute takes place. By this union the Sadhaka or the worshipper attains liberation, which is considered as the highest experience: a union of human life with the Universe. Once Kundalini Shakti has ascended to above the crown of the head and merged with Shiva, it is made to reverse its course and return to rest at the base of the spine.

Concept of Kundalini
According to the Tantric philosophy, the entire universe is the manifestation of pure consciousness. In manifesting the universe, this pure consciousness seems to become divided into 2 aspects, each of which cannot exist without the other. Each requires the other in order to manifest its total nature. The aspects are Shiva and Shakti. Shiva, the masculine part retains a static quality and remains identified as long as the consciousness is not manifested. Shiva has the power to be but not the power to change the world. The other aspect of the power is Shakti, which is feminine, dynamic, energetic and creative. Shakti is the Great Mother of Universe, from which all the other creatures are born.

According to the Tantra, the human being is the miniature of the Universe. All that is found in the cosmos can be found within the individual and the principle that applies in case of universe also applies in the case of individual being.

Practice of Kundalini Yoga
"Kundalini Awakening" is said to result in deep meditation, enlightenment and bliss. This awakening involves the Kundalini physically moving up the central channel to reach within the Sahasrara Chakra at the top of the head. Many systems of yoga focus on the awakening of Kundalini through meditation, pranayama breathing, practice of asana and chanting of mantras. In physical terms, one commonly reports the Kundalini experience to be a feeling of electric current running along the spine.