[2] In neidan, 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.

The Chinese compound nèidān combines the common word nèi 內 meaning "inside; inner; internal" with dān 丹 "cinnabar; vermillion; elixir; alchemy".

Traditional Chinese medical alchemical texts and sources ordinarily call neidan the jīndān dào 金丹道 or Way of the Golden Elixir.

In Modern Standard Chinese usage, the term nèidān shù 內丹術 (with 術 "art; skill; technique; method") refers generally to internal alchemical practices for longevity by maintaining good health, and the prevention of pain and suffering.

內丹 or neidan had been mentioned in 灵剑子 by Xu Xun 许逊 in Jin dynasty (266–420), but on the other hand Arthur Waley proposed that it was first recorded in the 559 vow taken by Tiantai Buddhist patriarch Nanyue Huisi praying to successfully make an elixir that would keep him alive until the coming of Maitreya.

I pray that all the saints and sages will come to my help, so that I may get some good magic mushrooms [zhi 芝], and numinous elixirs [shendan 神丹], enabling me to cure all illnesses and to stop both hunger and thirst.

[13] Neidan is part of the Chinese alchemical meditative tradition that is said to have been separated into internal and external (Waidan) at some point during the Tang dynasty.

The Shangqing School of Taoism played an important role in the emergence of neidan alchemy, after using Waidan mainly as a meditative practice, and therefore turning it from an external to an internal art.

[17] By means of internal alchemy, Taoists strive to maintain a positive free flow of qi through the body in paths or meridians moving to each individual organ.