Taiji is the short term for Taijiquan, and is often spelled "Tai Chi" in English. It is a special style of Martial Arts with a background strongly rooted in China's traditional culture. It embodies many profound theories, including Yin and Yang, Qigong, and the acupuncture meridians (channels and points). Instead of focusing on the strengthening of muscles, Taiji stresses the cultivation of "qi" and how it flows within the body. Taiji philosophy holds that the mind directs the circulation of "qi" and that this inner circulation of "qi" generates the external strength used in movement. The movements of taiji are spiral, with a strong intent on fighting efficiency. Taiji especially emphasizes the controlling of the opponent (qin na) and not being controlled (fan qin na). In practice, Taiji movements are slow and graceful, so it is suitable for people of all ages, especially elderly people. With its salubrious effects on health, it has had a strong appeal to more and more people throughout the world.