Martial arts are codified systems and traditions of combat practiced for a number of reasons such as self-defense; competition; physical, mental and spiritual development; and entertainment or the preservation of a nation's intangible cultural heritage. Tai chi short for T'ai chi ch'üan or Tàijí quán is an internal Chinese martial art practiced for both its defense training, its health benefits and meditation. The term taiji is a Chinese cosmological concept for the flux of yin and yang, and 'quan' means fist. So, etymologically, Taijiquan is a fist system based on the dynamic relationship between polarities (Yin and Yang).