The experience of Kundalini awakening can happen when one is either prepared or unprepared
According to Hindu tradition, in order to be able to integrate this spiritual energy, a period of careful purification and strengthening of the body and nervous system is usually required beforehand. Yoga and Tantra propose that Kundalini can be awakened by a guru (teacher), but body and spirit must be prepared by yogic austerities, such as pranayama, or breath control, physical exercises, visualization, and chanting. The student is advised to follow the path in an open-hearted manner.
Kundalini is considered to occur in the chakra and nadis of the subtle body. Each chakra is said to contain special characteristics and with proper training, moving Kundalini through these chakras can help express or open these characteristics.
Kundalini is described as a sleeping, dormant potential force in the human organism. It is one of the components of an esoteric description of the “subtle body“, which consists of nadis (energy channels), chakras (psychic centres), prana (subtle energy), and bindu (drops of essence).
Kundalini is described as being coiled up at the base of the spine. The description of the location can vary slightly, from the rectum to the navel. Kundalini is said to reside in the triangular sacrum bone in three and a half coils.
Swami Vivekananda describes Kundalini briefly in his book Raja Yoga as follows:
According to the Yogis, there are two nerve currents in the spinal column, called Pingalâ and Idâ, and a hollow canal called Sushumnâ running through the spinal cord. At the lower end of the hollow canal is what the Yogis call the “Lotus of the Kundalini”. They describe it as triangular in a form in which, in the symbolical language of the Yogis, there is a power called the Kundalini, coiled up. When that Kundalini awakens, it tries to force a passage through this hollow canal, and as it rises step by step, as it were, layer after layer of the mind becomes open and all the different visions and wonderful powers come to the Yogi. When it reaches the brain, the Yogi is perfectly detached from the body and mind; the soul finds itself free. We know that the spinal cord is composed in a peculiar manner. If we take the figure eight horizontally (∞), there are two parts which are connected in the middle. Suppose you add eight after eight, piled one on top of the other, that will represent the spinal cord. The left is the Ida, the right Pingala, and that hollow canal which runs through the center of the spinal cord is the Sushumna. Where the spinal cord ends in some of the lumbar vertebrae, a fine fiber issues downwards, and the canal runs up even within that fiber, only much finer. The canal is closed at the lower end, which is situated near what is called the sacral plexus, which, according to modern physiology, is triangular in form. The different plexuses that have their centers in the spinal canal can very well stand for the different “lotuses” of the Yogi.
When Kundalini Shakti is conceived as a goddess, then, when it rises to the head, it unites itself with the Supreme Being of (Lord Shiva). The aspirant then becomes engrossed in deep meditation and infinite bliss. Paramahansa Yogananda in his book God Talks with Arjuna: The Bhagavad Gita states:
At the command of the yogi in deep meditation, this creative force turns inward and flows back to its source in the thousand-petaled lotus, revealing the resplendent inner world of the divine forces and consciousness of the soul and spirit. Yoga refers to this power flowing from the coccyx to spirit as the awakened kundalini.
Paramahansa Yogananda also states:
The yogi reverses the searchlights of intelligence, mind and life force inward through a secret astral passage, the coiled way of the kundalini in the coccygeal plexus, and upward through the sacral, the lumbar, and the higher dorsal, cervical, and medullary plexuses, and the spiritual eye at the point between the eyebrows, to reveal finally the soul’s presence in the highest center (Sahasrara) in the brain