You may hear it called many things. Like Kundalini-Sakti, Serpent Power, Goddess (Devi) Kundalini, Shakti, The Holy Spirit or just plain Kundalini. She is the Divine Cosmic Energy in the body. Her movement is serpentine so its often described as snake like. For most people, it lies at your root Chakra. Its located at the base of the spine near the perineum. It sleeps there and remains coiled three times.
All the Yogas are methods to help awaken the Kundalini. The goal is to have the Kundalini to rise through the seven Chakras (Energy Centers)and obtain Enlightenment. When the Kundalini passes the Seventh Chakra (Crown Chakra), she unites with Siva which is the masculine part of the Universe. You become one with the cosmic consciousness while still in your living body. You become one with your Higher Power. This state is supposedly blissful and ecstatic. I have read in yogic texts that the Kundalini then goes back down your Chakras and rests again in the Root Chakra. You have reached Enlightenment.
It use to be that serious yoga practices were needed to rise the Kundalini but that is no longer the case. Some people are raising their Kundalini just by meditating. Others are having spontaneous Kundalini Awakenings without any vigorous spiritual practices at all.
Kundalini Awakenings can cause many symptoms as it rises to the Crown Chakra. I will write about this in detail in a future entry. It has been my own personal experience that when you surrender to the Kundalini and allow it to do its works, there are less symptoms.
Kundalini Awakenings can happen quickly or over many years. The Kundalini has to remove blockages and emotional junk before it can rise to your Crown Chakra.
Kundalini is not bad or evil. Its the Divine working through your energy centers so you can Evolve!
I am sure I will be adding more as time goes on.