The fullest early technical account of kundalini appears in Hatha Yoga and tantric literature such as the Hatha Yoga Pradipika, the Shiva Samhita and the Sat-Cakra-Nirupana, which describe her as a coiled, sleeping serpent, kundalini meaning "coiled one," resting at the base of the sushumna nadi inside Muladhara, the root chakra, where she is said to close the mouth of the central channel with three and a half coils around a svayambhu linga. Practice aims to wake her through a combination of pranayama (breath retention), bandhas (bodily locks, especially mula bandha at the perineum), mudras and mantra, forcing the accumulated prana to strike the base of sushumna until kundalini uncoils and begins to rise.
As she ascends she is said to pierce each chakra in sequence, and her arrival at Sahasrara, the crown, is described as the union of Shakti, the goddess-power she embodies, with Shiva, consciousness itself, said to reside there; this union is the tantric image of liberation, not a metaphor added afterward. The texts are explicit that this is advanced, dangerous practice, to be undertaken only under a qualified guru's supervision after the body and channels have been purified by preliminary yogic disciplines, and several warn plainly of physical and mental harm from forcing kundalini without that preparation.