What is "neijing"

In advanced traditional Chinese kung fu ( martial arts), Neijing ( Traditional Chinese: 內勁; pinyin: nèijìng) refers to the conscious control of the practitioner's qi, or "life energy", to gain advantages in combat. Nèijìng is developed by using " Neigong" (Traditional Chinese: 內功; pinyin: nèigōng) , or "internal exercises," as opposed to "wàigōng" , "external exercises."