Tai-chi-chuan; perhaps the best known of the internal Chinese styles, tai chi can be broken down into four significant varieties-yang, wu, chen and sun. Although tai chi is a martial art, it is more commonly used as a healing art. It is widely believed that practicing tai chi's slow, graceful movements can increase blood circulation, develop flexibility, aid in the function of the heart, liver and kidneys, add years to one's life, and improve one's overall health. As a method of self-defense, tai chi trains practitioners how to use an attacker's energy against him; they almost never meet force with force. Practitioners first learn about their own balance, then they learn to recognize the balance of others.