Taichi is the shortend name of the Chinese Martial Art called Tai'Chi Chu'an (some times also spelled as Taiji Quan). Taichi means "Grand Ultimate". The peak of a mountain is also called "taichi". Also "the heavens" or "cosmos" are called taichi. Chuan means "fist" or "boxing". Tai'chi Chu'an is the "Grand Ultimate Boxing Style".

Although it's roots are in ancient Chinese Martial Arts, and it still can be taught as self defense, Taichi is now mainly practiced for the health benefits. It is a low-to-no impact form of exercise, practiced in slow motion, placing emphasis on proper posture and body movements. Also included is qigong or breathing exercises that can also be therapeutic in nature.

T'ai Chi Ch'üan is considered a soft style martial art, an art applied with deep relaxation or "softness" in the musculature as possible, to distinguish its theory and application from that of the hard martial art styles which use a degree of tension in the muscles.

Variations of T'ai Chi Ch'uan's basic training forms are well known as the slow motion routines that groups of people practice every morning in parks across China and other parts of the world. Traditional T'ai Chi training is intended to teach awareness of one's own balance and what affects it, awareness of the same in others, an appreciation of the practical value in one's ability to moderate extremes of behavior and attitude at both mental and physical levels, and how this applies to effective self-defense principles.

The main styles of Tai Chi Chuan are Chen, Yang, Wu, and Sun. The Wu and Sun styles branched off of Yang style, and Yang off of Chen style, making the Chen style the ancestor of all styles of Tai Chi Chuan. Thus it is said that Tai Chi history, techniques, and theory may not be discussed without including a discussion of the Chen style. The following description of Tai Chi and its history is based on the on obervations and history about the art given by the famous Chinese martial arts historian Tang Hao (1897~1959) in his book The Development and Sources of Tai Chi Chuan.

Tai Chi Chuan is said to have been founded by Chen Wang Ting, a general living at the end of the Ming dynasty and the 9th generation descendant of the Chen family in Chen Village, Henan Province. At the end of his career the Ming Dynasty was dying, giving way to the Qing, so Chen, who was aging at the time, retired to the study of martial arts. He studied the various arts of the time, and created a new art based on his studies modeled after the principles of the I-Ching, which he called Tai Chi Chuan (Grand Ultimate Boxing, after the Taoist principle of the Grand Ultimate). Chen Wang Ting adopted for Tai Chi twenty-nine out of the thirty-two postures given in the Boxing Scriptures section of the Ji Jiao New Book, a book compiled three hundred years before Chen?s time by the famous Qi Ji Guang, skilled in the art of battle, for use by his soldiers in their war against the Wo Kou.

Historically, T'ai Chi Ch'uan has been regarded as a martial art, and its traditional practitioners still teach it as one. Even so, it has developed a worldwide following among many thousands of people with little or no interest in martial training for its aforementioned benefits to health and health maintenance. Some call it a form of moving meditation, and T'ai Chi theory and practice evolved in agreement with many of the principles of traditional Chinese medicine. Besides general health benefits and stress management attributed to beginning and intermediate level T'ai Chi training, many therapeutic interventions along the lines of traditional Chinese medicine are taught to advanced T'ai Chi students.

The physical training of T'ai Chi Ch'uan is described in the writings of its older schools as being characterized by the use of leverage through the joints based on coordination in relaxation, rather than muscular tension, in order to neutralize or initiate physical attacks. The slow, repetitive work involved in the process of learning how that leverage is generated gently and measurably increases and opens the internal circulation: (breath, body heat, blood, lymph, peristalsis, etc.). Over time, proponents say, this enhancement becomes a lasting effect, a direct reversal of the constricting physical effects of stress on the human body. This reversal allows much more of the students' native energy to be available to them, which they may then apply more effectively to the rest of their lives; families, careers, spiritual or creative pursuits, hobbies, etc.

The study of T'ai Chi Ch'üan involves three primary subjects:

Health - an unhealthy or otherwise uncomfortable person will find it difficult to meditate to a state of calmness or to use T'ai Chi as a martial art. T'ai Chi's health training therefore concentrates on relieving the physical effects of stress on the body and mind.
Meditation - the focus meditation and subsequent calmness cultivated by the meditative aspect of T'ai Chi is seen as necessary to maintain optimum health (in the sense of effectively maintaining stress relief or homeostasis) and in order to use it as a soft style martial art.
Martial art - the ability to competently use T'ai Chi as a martial art is said to be proof that the health and meditation aspects are working according to the dictates of the theory of T'ai Chi Ch'üan.
In its traditional form (many modern variations exist which ignore at least one of the above requirements) every aspect of its training has to conform with all three of the aforementioned categories.

The Mandarin term "T'ai Chi Ch'uan" translates as "Supreme Ultimate Boxing" or "Boundless Fist". T'ai Chi training involves learning solo routines, known as forms, and two person routines, known as pushing hands, as well as acupressure-related manipulations taught by traditional schools. T'ai Chi Ch'uan is seen by many of its schools as a variety of Taoism, and it does seemingly incorporate many Taoist principles into its practice (see below). It is an art form said to date back many centuries (although not reliably documented under that name before 1850), with precursor disciplines dating back thousands of years. The explanation given by the traditional T'ai Chi family schools for why so many of their previous generations have dedicated their lives to the study and preservation of the art is that the discipline it seems to give its students to dramatically improve the effects of stress in their lives, with a few years of hard work, should hold a useful purpose for people living in a stressful world. They say that once the T'ai Chi principles have been understood and internalized into the bodily framework the practitioner will have an immediately accessible "toolkit" thereby to improve and then maintain their health, to provide a meditative focus, and that can work as an effective and subtle martial art for self-defense.

Orthodox T'ai Chi schools say the study of T'ai Chi Ch'uan is studying how to change appropriately in response to outside forces. These principles are taught using the examples of physics as experienced by two (or more) bodies training for combat. In order to be able to protect oneself or someone else by using change, it is necessary to understand what the consequences are of changing appropriately, changing inappropriately and not changing at all in response to an attack. Students, by this theory, will appreciate the full benefits of the entire art in the fastest way through physical training of the martial art aspect.

Wu Chien-ch'üan, co-founder of the Wu family style, described the name T'ai Chi Ch'üan this way at the beginning of the 20th century:

"Various people have offered different explanations for the name T'ai Chi Ch'uan. Some have said: 'In terms of self-cultivation, one must train from a state of movement towards a state of stillness. T'ai Chi comes about through the balance of yin and yang. In terms of the art of attack and defense then, in the context of the changes of full and empty, one is constantly internally latent, not outwardly expressive, as if the yin and yang of T'ai Chi have not yet divided apart.'
Others say: 'Every movement of T'ai Chi Ch'uan is based on circles, just like the shape of a T'ai Chi symbol. Therefore, it is called T'ai Chi Ch'uan.' Both explanations are quite reasonable, especially the second, which is more complete."