This is a good question but a rather difficult one to answer because taijiquan defies a strict definition. However, the most basic answer is that taijiquan is a life-nourishing, internal martial art from China. To get any kind of idea of what taijiquan is, this answer is way too short. Therefore, we will try to explain it in some more detail. Taijiquan consists of several general aspects, all of which are inherent to each other. These are: philosophy, martial art, well-being and self-cultivation.
Taijiquan belongs to the Chinese martial arts (wushu). Wushu is the collective name for all Chinese martial arts that can be divided into three main groups, namely: 1. The attacking school, 2. The defensive school and 3. The neutral school. Taijiquan belongs to the last one.
This is also apparent from the name of this discipline. “Quan” can be translated as boxing and “taiji” is the name of a philosophical school. This philosophical school embodies the teachings of yin-yang, or complementary opposites, which in relative and comparative terms express the reality of a particular situation. However, yin-yang is continuously subject to change. Since change is perpetual and continuous, the basic stance is not to go against it. This stance implies finding and/or maintaining a harmonious equilibrium between these two forces by going along with it in the most relaxed way possible. The sum of the two terms, taiji and quan, thus describes a martial methodology that follows the principles of yin-yang.
The transition of yin-yang is cyclic in nature and is therefore often represented as a circle. Subsequently the movements of taijiquan are executed in a round manner. This enables the practitioner to follow the transformations of yin-yang and/or to blend with and follow the opponent’s movements. In doing so, the practitioner makes use of the neutralizing and counter-active quality of roundness, which ultimately causes the opponent to unbalance him/herself.
However, this strive to maintain balanced is not limited to the opponent, it also applies to the practitioner (for example body and mind). Taijiquan strives to strengthen this balance by combining relaxed bodily movement with a serene mental mind-set. In order to support the physical relaxation, the movements (initially) are carried out in a slow, circular, and smooth manner. In this way the body is strengthened without overstraining it. Even so, this way of moving demands a high level of mental involvement. On the one hand, this enhances the reciprocal connection of body and mind. On the other, it opens the door to self-reflection and ultimately to self-cultivation.
What all systems of taijiquan have in common is their aim to cultivate physical stillness and conscious movement. In this, breathing plays a crucial role. Proper breathing not only guides the mental faculties, it also confers a vital impulse to the body. Properly executed, the result is a heightened awareness of oneself (that increase over time with continued practice). This heightened awareness enables one to become sensitive to all sorts of (subtle) internal feelings, like circulation, balance, alignment, movement etc. and the feeling of internal energy, called Qi. Consequently, diligent practice will enhance our state of being, but it also imparts the ability to correct possible imbalances, encountered during practice, in the long run.
Taijiquan is unique in that it combines all of these aspects into one system and gives you all the tools to boost yourself!