Kundalini or serpent power does not belong to the physical body, nor does it belong to the mental body it exists in the astral body. Kundalini literally means a coiled up energy or the power that dwells in a cave (kunda). For any transformation to be possible energy is needed to bring it about. For the transformation of consciousness a special & powerful energy is needed. That is kundalini. The term “KUNDALINĪ” is based on several words, and therefore has several meanings.

The word-ending “ī” indicates that it relates to the feminine principle and deals with a form of SHAKTI (energy) and PRAKRITI (nature).

• KUNDA is a hole or well into which all debris and rubbish is thrown. Our impressions from earlier lives lie like an amorphous substance deep in the unconscious (Mūlādhāra Chakra).
• KUNDALA means ring (generally earring). A ring or a circle has neither a beginning nor an end. It is infinite and that is why it is a symbol of creation. Cosmic energy is circling constantly; we do not know when the Universe began and how long it will last.

The 3 coils of snake also represents 

3 Gunas (tamsik, rajshik, sattvic). 

3 states of consciousness (sleeping, waking, dreaming)

3 types of experience (subjective, sensual & absence of obj)

And half coil represents the state of transcendence where there is neither waking, sleeping or dreaming. So the 3 & a half coil represents the total experience of the universe & the experience of transcendence.

Kundalini is the study if Tantra Yoga, & hence Kundalini is considered as the form of Goddess & should be worshipped as HER power. Tantric science has its foundation in vedic & yogic teachings, that speak about the transforming word (vak), the energy of consciousness (chit-shakti) or the power of knowledge (janana-shakti), which are all symbols of kundalini.

According to tantra vidya, it is not a psychic energy to be aroused but a Divine energy to be revered. Efforts to manipulate kundalini through willful practice or forceful techniques are not only dangerous, but fail to recognize the reality of the Goddess and are contrary to her worship. The arousing of the Kundalini can occur through devotion or profound meditation & does not require the use of specific Yoga techniques. 

When Yoga techniques are used to arouse the Kundalini – and they are often very helpful, they should be done as a part of practice of surrender to Divine or inquiry into the self nature. The Yoga student should first have a background in meditation, control of senses & an understanding of the working of the mind before trying to arouse the Kundalini.