Neidan

Neidan, or internal alchemy (simplified Chinese: 內丹术; traditional Chinese: 內丹術; pinyin: nèidān shù), is an array of esoteric doctrines and physical, mental, and spiritual practices that Taoist adepts use to prolong life and create an immortal spiritual body that would survive after death. Also known as Jindan ("golden elixir"), inner alchemy combines theories derived from external alchemy (waidan), correlative cosmology (including the Five Phases), the emblems of the Yijing, and medical theory, with techniques of meditation, daoyin gymnastics, and sexual hygiene.