The correct name for "T'ai Chi" is Taijiquan. This is the spelling method (pinyin) that has been used in Mainland China since 1956. It is also the method used by the United Nations.
Taijiquan is pronounced, in a Kiwi accent "Tie-jee (as in jeep)- chew-un". The word that is missing from the name "T'ai Chi" is Ch'uan (quan). This word means fist or fighting. The meaning of Taijiquan is: the most efficient fighting method. In old China, Taijiquan was often referred to as "thinking boxing".
The old way of writing Taijiquan is still used in Taiwan (T'ai Chi Ch'uan) and the reasons for that are both historical and political, but the pronunciation is the same in both cases. Unless you have studied Chinese language, the subtleties of the spelling will not be apparent, but for interest sake, look at the use of apostrophes and how the pronunciation of "Ch" changes, with or without one. The reason the name "T'ai Chi" is used in New Zealand, is due to the way in which it left China, and was introduced to the West.
The origins of Taijiquan go back 2500 years into ancient China. Taijiquan is a combination of a preventative health system (QiGong) and a Martial Art - WuShu (KungFu):
Taijiquan was devised to overcome the age related problem. Using Martial techniques combined with the body's innate energy, older Martial Artists found a way to maintain their WuShu and longevity. These techniques however, relied on the use of the mind, not just physical skills; so many years were needed to become an expert in the art of Taijiquan. The use of the mind incorporated the Daoist (Taoist) philosophy of combining with an incoming force and redirecting it, rather than attacking it or trying to stop it. It was this change of Martial philosophy, which made Taijiquan become the most efficient 'internal' school of Martial Arts.
Because Taijiquan took such a long time to master, the methods were carefully guarded by masters of the art, as this ensured their, and their family's, livelihood. It was from these families, that the names of the main traditional styles came - Chen, Yang, Wu, Hao, and Sun.

This is the book we use
for teaching the form
and can be bought from
WahLee
In modern times (after 1940's) Taijiquan methods were taken from both within and outside of China, and promoted and propagated by many insufficiently trained, though enthusiastic people (and even governments!). This has lead to a plethora of instant or simulated copies of the original concepts. Many of the original ideas were simplified, and the focus of Taijiquan changed to become physical exercise oriented. Anyone considering taking up Taijiquan, even as an exercise option, should be discerning about what they are intending to participate in, because if Taijiquan is performed incorrectly, one can waste time, effort and money.
The purpose of Taijiquan is to increase longevity by cultivating qi through physical training, and control the mind through mental training. Initially, physical shapes and movement patterns are taught, and then once one has perfected these patterns, mind control is taught. Some effects of applied Taijiquan training include: increased vitality, sharper concentration, increased flexibility and strength, an overall sense of well-being and confidence and an acute sense of 'self'. Taijiquan is suitable for people of all ages, though the younger one starts training, the longer they have to develop themselves. The effects of Taijiquan begin as soon as one starts correct training.
Today most people want an accessible method of exercise that will maintain and improve their health, concentration, efficiency and sense of well-being. There are thousands of documented cases of the restorative effects of Taijiquan, even as far as curing chronic illnesses. In fact, one teacher I have was cured of T.B. by taking up Wu Style Taijiquan, when all his family died of the disease. I personally recovered from viral encephalitis (and subsequent craniotomy and cranioplasty) by practicing Wu Style Taijiquan.
Performed correctly, Taijiquan looks like a slow motion dance routine that never stops and has postures that look like Kungfu shapes. It is deceptive in its appearance. Beneath the outwardly tranquil exterior characterized by stillness, agility, and continuity is an exercise system designed to use every muscle in the body, to strengthen and stretch them, to subconsciously teach a defensive martial art, as well as concentrate the mind.
However, the effects of Taijiquan will only be reaped if learned and practiced correctly. Once your "form", or pattern, is learned, you only need to continue to practice it every day for it to work.
If you are reading this then you are alive and thus you must have a life force (qi). Taijiquan is about maximizing the benefits of that qi. Those benefits can only be realized through regular practice that is accurate, persistent and patient.