Internal Martial Art

The term "nèijiā" usually refers to the internal styles of Chinese martial arts, which Sun Lutang identified in the 1920s as T'ai Chi Ch'uan, Xíngyìquán and Bāguàzhǎng. This classifies most other martial arts as "wàijiā" (lit. "external/outside sect"). Some other Chinese arts, such as Liuhebafa and Yiquan are frequently classified (or classify themselves) as internal or having internal qualities. These secondary neijia may be related to, or derived from, the primary arts.
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Les arts martiaux internes (内家拳 appelé aussi arts du poing interne ou Nei Jia Quan) sont attachés au courant taoïste et proviennent du Mont Wudang. Ils sont basés sur le développement de l'énergie (QI) et des chakras (qui sont les points énergétiques du corps).
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Mit dem Begriff innere Kampfkünste (, kurz neijia) werden einige Stile der chinesischen Kampfkünste bezeichnet, die in enger Verbindung zum philosophischen Daoismus stehen und häufig mit den daoistischen Klostern der Wudang-Berge in Zusammenhang gebracht werden. Die bekanntesten davon sind Taijiquan, Baguazhang sowie Xingyiquan, jedoch existieren zahlreiche weitere Stile, die zu den inneren Kampfkünsten gezählt werden (siehe Liste der Kampfsportarten).
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T'ai Chi Ch'uan ("Grand Ultimate Fist") been described as an Internal Martial Art. This indicates that the emphasis is placed on strengthening the mind, circulating the Chi or vitality, and relaxing the body so that it's free to move. This is dramatically different from the external styles (Karate, Kung Fu, etc.) in which the emphasis is placed on physical strength, speed, and technique.
Although other T'ai Chi practitioners may disagree with me, I feel that T'ai Chi as a martial art has virtually nothing to do with learning self-defense, although these skills can be developed in the practice. Rather I have been trained to understand the martial art aspect of T'ai Chi , which includes study of application, push-hands  , and full contact sparring, to be the use of intense and demanding situations to observe old patterns of reacting with fear and aggression, and systematically replacing them with awareness and relaxation.
My teachers, all native Chinese and truly accomplished
martial artists, seem to share one basic skill; freedom from fear. If I have experienced one core benefit from the martial aspect of T'ai Chi training it has been a lessening of fear (fear of pain, fear of injury, fear of the future) which leads to a sense of calm confidence. This is the emotional component of the ability to respond well to demanding situations and an aspect of true martial art proficiency.