Kundalini, the serpent power or mystic fire, is the primordial energy or Sakti that lies dormant or sleeping in the Muladhara Chakra, the centre of the body. It is called the serpentine or annular power on account of serpentine form. It is an electric fiery occult power, the great pristine force which underlies all organic and inorganic matter.
Kundalini is the cosmic power in individual bodies. It is not a material force like electricity, magnetism, centripetal or centrifugal force. It is a spiritual potential Sakti or cosmic power. In reality it has no form. The Sthula Buddhi and mind have to follow a particular form in the beginning stage. From this gross form, one can easily, understand the subtle formless Kundalini. Prana, Ahamkara, Buddhi, Indriyas, mind, five gross elements, nerves are all the products of Kundalini.
It is the coiled-up, sleeping Divine Sakti that lies dormant in all beings. You have seen in the Muladhara Chakra that there is Svayambhu Linga. The head of the Linga is the space where Sushumna Nadi is attached to the Kanda. This mysterious Kundalini lies face downwards at the mouth of Sushumna Nadi on the head of Svayambhu Linga. It has three and a half coils like a serpent. When it is awakened, it makes a hissing sound like that of a serpent beaten with a stick, and proceeds to the other Chakra through the Brahma Nadi, which is also called Chitra Nadi within Sushumna. Hence Kundalini is also called Bhujangini, serpent power. The three coils represent the three Gunas of Prakriti: Sattva, Rajas and Tamas, and the half represents the Vikritis, the modification of Prakriti.
Kundalini is the Goddess of speech and is praised by all. She Herself, when awakened by the Yogin, achieves for him the illumination. It is She who gives Mukti and Jnana for She is Herself that. She is also called Sarasvati, as She is the form of Sabda Brahman. She is the source of all Knowledge and Bliss. She is pure consciousness itself. She is Brahman. She is Prana Sakti, the Supreme Force, the Mother of Prana, Agni, Bindu, and Nada. It is by this Sakti that the world exists. Creation, preservation and dissolution are in Her. Only by her Sakti the world is kept up. It is through Her Sakti on subtle Prana, Nada is produced. While you utter a continuous sound or chant Dirgha Pranava ! (OM), you will distinctly feel that the real vibration starts from the Muladhara Chakra. Through the vibration of this Nada, all the parts of the body function. She maintains the individual soul through the subtle Prana. In every kind of Sadhana the Goddess Kundalini is the object of worship in some form or the other.
Kundalini has connection with subtle Prana. Subtle Prana has connection with the subtle Nadis and Chakras. Subtle Nadis have connection with the mind. Mind has connection all through the body. You have heard that there is mind in every cell of the body. Prana is the working force of the body. It is dynamic. This static Sakti is affected by Pranayama and other Yogic practices and becomes dynamic. These two functions, static and dynamic, are termed ‘sleeping’ and ‘awakening’ of the Kundalini.