Neidan, or internal alchemy (traditional Chinese: 內丹術; simplified Chinese: 內丹术; pinyin: nèidān shù), is an array of esoteric doctrines and physical, mental, and spiritual practices that Taoist initiates use in hopes to prolong life and create an immortal spiritual body that would survive after death. Also known as Jindan (金丹 "golden elixir"), internal alchemy combines theories derived from external alchemy (waidan 外丹), correlative cosmology (including the Five Phases), the emblems of the Yijing, and medical theory, with techniques of Taoist meditation, daoyin gymnastics, and sexual hygiene.
In neidan practice, Taoists claim the human body becomes a cauldron (or "ding") in which the Three Treasures of Jing ("Essence"), Qi ("Breath") and Shen ("Spirit") are 'cultivated' for the purpose of improving physical, emotional and mental health, and ultimately returning to the primordial unity of the Tao, i.e., attaining Taoist Immortality. It is believed the Xiuzhen Tu is such a cultivation map. In China, this act is an important form of practice for most schools of Taoism.