Kundalini is the name of a sleeping dormant potential force in the human organism and it is situated at the root of the spinal column. In the masculine body it is in the perineum, between the urinary and excretory organs. In the female body its location is at the root of the uterus, in the cervix. This center is known as mooladhara chakra.
To awaken kundalini you must prepare yourself through yogic techniques. You must practise asanas, pranayama, yoga and meditation. Then, when you are able to force your prana into the seat of kundalini, the energy wakes up and makes its way through sushumna nadi, the central nervous canal, to the brain. As kundalini ascends, it passes through each of the chakras which are interconnected with the different silent areas of the brain. Therefore, kundalini can be equated with the awakening of the silent areas of the brain.
Whatever happens in spiritual life, it is related to the awakening ot kundalini. And the goal of every form of spiritual life, whether you call it samadhi, nirvana, moksha, communion, union, kaivalya, liberation or whatever, is in fact awakening of kundalini.
