The Chinese expression nei gong (lit. nei: inside, gong: labor) covers a wide range of internal practices of Taoist tradition, associated with the internal martial arts (neijia quan), essentially the xingyi quan, the bagua zhang and of course taiji quan.
The nei gong includes breathing exercises, meditation, as well as a wide range of bodily practices, both dynamic and static, on heating and relaxation (ji ben gong), relaxation (song shen wu fa) , postures (zhan zhuang) and energy (qi gong).
Nei gong is part of Taoist alchemical practices, which consist of an internal transformation of the practitioner, a progression from crude to subtle: from jing (the substance, the physical body in the broad sense) to qi (the energy, vital breath) and shen (consciousness, spirit) *. These exercises, in addition to catalyzing this transformation, can also serve more immediate purposes, ranging from health, physical and mental to martial and spiritual.
* Jing, qi and shen constitute the Three Treasures (san bao), central concept of the Taoist tradition.