The most important nadi is the sushumna nadi. Most texts agree that this channel begins in the muladhara chakra  at the base of the spine. The channel corresponds to the Governor Vessel meridian in the Daoist view of energy flow. The sushumna flows inside the core of the spine, but it is not the spine; it is subtler than that. The perceived function of the sushumna depends upon the school of yoga one is studying. Dr. Motoyama claims that the sushumna governs the six yang meridian lines, but here he is combining his unique experience of both yoga and Daoism to explain the way our body works.
In Tantra and Kundalini Yoga, and in many Hatha Yoga schools, the sushumna is the key channel within which shakti energy  flows. Kundalini is said to be a special form of energy or the highest form of prana. The term refers to the power of the snake, which is envisioned to lie curled in three and a half coils at the base of the spine, dormant and awaiting wakening. 
Georg Feuerstein in the Shambhala Encyclopedia of Yoga explains that prana may be considered like the energy in an atomic bomb, while kundalini energy is like that of a hydrogen bomb. An apt metaphor as the release of this energy is quite dramatic. Shakti energy is directed upward from its home just below the muladhara chakra toward the ajna chakra (according to Dr. Motoyama) or the sahasrara (according to Georg Feuerstein).  The intention is to bring kundalini up the sushumna to the top of the head where Shiva awaits reunion with Shakti. 
Once the kundalini has been awakened and raised up the sushumna to the top of the head, many psychic phenomena may occur. Inner sounds, special sight, and insights can be perceived. Vibhutis  may be manifested such as clairvoyance, telekinesis, telepresence, and telepathy. Living liberation is achieved in this manner – that is, liberation while still residing in the body.
- — See the Chakra section for details.
- — Sometimes called the kundalini energy.
- — Sometimes we find shakti written with a capital S and sometimes without. When the word is capitalized, it generally refers to the goddess Shakti. When it is not capitalized, it is referring to the energy of the goddess but not the goddess herself. But don’t be alarmed if this is not universally done.
- — The chakras mentioned above will be defined a little later in our journey.
- — Again here we find very different models taught by different sages. Many schools claim the kundalini energy is supreme and must be stimulated to rise up the central channel. These teachers make a distinction between the kundalini awakening and the activation of ordinary prana. Others, such as the sage who wrote the Yoga Yajnavalkya, claim the kundalini snake at the base of our spine is an impediment, a blockage, which must be burned away before prana can rise. The snake is a guardian of the gate to the sushumna and must be woken up so it can be moved away. In this model, it is just prana that needs to be concentrated in the body and directed up the sushumna nadi. And yet another school claims that Shakti’s energy actually descends downward to meet Shiva, who is awaiting her at the base of the spine. This is represented in the Shri Yantra where the downward-facing triangles are said to be Shakti and the upward-facing triangles are Shiva, pointing in the same direction his symbolic lingam is always pointing. We can avoid being confused if we consider the different teachings as simply different models; do not try to use one model to explain the symbolism of another model.
- — Vibhutis are special powers.