1. It is present in the form of energy. When people experience with qi, it is often described in the form of bodily sensations such as warmth, coolness, a feeling of bloating, pain, itchiness and/or numbness. These sensations are similar to the sensations we experience when we have contact with other forms of energy that we understand such as numbness in electricity, coolness in ice, and warmth in fire, etc.
2. It circulates in space in the form of molecules. Although it is so small that we cannot see it with the naked eye, but we can detect its presence with our other senses such as feeling or smell. e.g. We often smell flowers when we come close to them and the same thing with foods. This is so because the molecules that carry the fragrant odors of flower and food circulate in space; when we contact with any of these molecules, we smell flowers and food. The same principle can be applied to qigong practice when the practitioner detects or smell fragrant odors while in qigong condition.
3. It transmits as a field, wave after wave in all directions, as in an electrical field or an electromagnetic field.

The Qi Composition
We can say the qi inside the body comes from five sources. It comes from the air we breathe, from the food we eat, from our parents, from the environment and the internal qi or the combination of all the above.

1. Breathing qi
   Regeneration is a natural process that nobody can stop. Through this process, the body obtains oxygen from outside the body and removes carbon dioxide from the body. This kind of exchange with our environment is called breathing. This process involves the lungs, bronchi, alveolus sac and the chest cavity. The bronchi transport the air, the alveolus sac is the actual exchange location where the blood intakes oxygen and removes carbon dioxide. Generally, air exchange in the lung is considered the external breathing and blood cells exchange of oxygen is consider internal breathing. The skin that covers our body is not just for protection and transmission. It is also a breathing vehicle in contact with the environment through the hair follicles on the skin. Among the breathing methods described above, the most important method is breathing with the lung because it is the major source of the body's oxygen intake. Internal breathing is the result of breathing with the lung combining with the qi derived from foods. Breathing through the hair follicles on the skin only function as a supporting role.
2. Food qi
   We need food and nutrients regularly for the body's growth and daily activities. Most of the nutrients come from the food we eat. They come from the process of digestion by the stomach and absorption by the intestines. These nutrients are transported throughout the body by blood circulation. The food qi has two functions. The first function is to protect the body from pathogens. This form of the food qi is called the "Wei" or protective qi. Its activity outside of the meridians. The second function of the food qi is as "Ying" or nutritive qi which provides the body with the necessary nutrients. These two kinds of qi exist throughout the body and provide nutrients and protection.
3. Original qi
   Original qi is something which we are born with. It is different from the qi from breathing or derive from the food we eat. It comes from the parents. It is also called the primordial qi. This is the qi that determines and maintains life. When this original qi weakens, one will be sick. This weakness can be supplement by the "post-birth" qi or the qi from food and breathing. Because one can supplement the other, it is difficult to separate the original qi from the post-birth qi. Therefore, it is difficult for people to understand the difference between the two.
4. Environmental qi
   The Tai Chi Chuan Classics said "Wu Chi is the origin of Tai Chi. Tai Chi is the origin of the Two Elements, Two Elements are the origin of the Four Phenomenon, the Four Elements are the origin of Pa Kua and Pa Kua is the origin of everything or all things come from Pa Kua". From this statement, Wu Chi is the originator of all things. This also refers to today's concepts of environmental or universal qi. There are two techniques to obtain this environmental qi.
   1. Environmental qi is a special kind of energy, it requires a very special technique to get it. The technique requires the practitioner to be in harmony with or combine with the environment with proper orientation and discipline so that the body qi will exchange with the environmental qi. The exchange involves breathe out all the bad qi or sick qi and breathe in or absorb all the environmental qi. Besides applying the mouth to breathe, it involves the hair follicles on the skin as well. This qi will improve the body's condition, prolong life and cultivate the ability to heal others. The mechanics of this kind of breathing involve using the whole body as a conscious act. It is different from breathing with the lungs which mainly draw in oxygen.
   2. The second technique is the practitioner channel this environmental qi to heal others. From this channeling, the practitioner emits qi onto the patient through certain acupuncture points and as the same time, retain residue or certain amount of qi remain with the practitioner's own body.
5. Internal qi
   Internal qi is the product of internal practice following the guidance of intent, combined with the breathing qi, food qi, original qi and environmental qi.
   The Internal qi's primary component is the original qi, the secondary component is the environmental qi, food qi is the initial source of energy of this combination and breathing qi is the application of this combination. Everyone has the ingredients to produce this internal qi or to combine the original qi, environmental qi, food qi and breathing qi. However, not everyone has internal qi. Internal qi belongs only to those practitioners who follow the restricted discipline of internal practice.
   Besides the functions and characteristics described above, internal qi also differs from the other four forms of qi in the following ways:
   1. The four types of qi described above circulate automatically inside the body. They are not under our conscious control. Internal qi, on the other hand, is able to follow our command and can move quickly or slowly to coordinate with our physical motion.
   2. The four qis described above each have their own functions. eg. food qi circulates inside the meridians and original qi is responsible for our physiologic organs' functions. These kinds of solo functions are very different from the internal qi which circulates throughout the body. Therefore, the internal qi has greater function and application.
   3. The four qis can maintain physiologic organs' functions and healthy condition. Internal qi can lead the practitioner to developed psychic abilities, increase bone density, improve physical strength, body endurance and improve mental capacity and creativity.
   4. Internal qi is the product of internal practice. The amount of internal qi is determined by the quantity of internal practice.
      These five kinds of qi described above are often referred to as the qi inside the body. It is difficult to distinguish them because they are inter-related.

In ancient China, qigong had many names. They were names based on the techniques, the emphasis, the objectives and the benefits. Generally, qigong techniques divided into five major schools. They are The Medical Qigong School to strengthen one's health, and heal and prevent disease. The Confucian Qigong School is for one's self-cultivation and temperament. The Taoist Qigong School is for one's cultivation of moral character, longevity and harmony with the environment. The Buddhist Qigong School aims to train and purify one's mind. The Martial art Qigong School is training for one's physical strength and improving health.

Although there are five major schools and thousands of qigong techniques, qigong practices are generally divided into Physical and Spiritual forms of practice. A practitioner begins with one of the two. They are opposite, yet complementary. They both exist in all things. One should not recognize them as two separate things. The practices that emphasize the Physical involve the two human treasures: essence and qi. If a person regularly practices and cultivates these two things he will improve his physical health. These practices that emphasize the Physical make use of the conscious spirit. Through these types of practice one becomes more fully aware physical objects or physical reality. When speaking of physical reality we mean those things which have shape, mass, occupy space and can be seen.

The practices that emphasize the Spiritual utilize the unconscious spirit. Through these practices one become more fully aware of the non-physical objects, it is commonly refer to as the spiritual reality, or those things which do not have shape or mass, do not occupy space and cannot be seen.

A correct and advance qigong technique must include both the Spiritual and the Physical. It is often said that if one practices only the Physical that this is the first disease in training. It is also said that if one only practices the Spiritual, that person will never achieve high level and skill.

The experiences, emphasis and priorities adopted by qigong practitioners over the years divided qigong training into five major schools which exist today. Although there are numerous techniques among the schools, all of these techniques can generally be divided into their dynamic and static components based on the physical requirement.

The static components deal with the spiritual body and the tranquility condition of the intent. This is the best method to improve health and longevity. The dynamic components deal with the physical body and the dynamic condition of the internal qi. The dynamic aspects emphasize physical movement, and also emphasize the coordination of power, breathing, intent and physical movements.

Both the dynamic and static components each have their separate special functions. Although the static component also trains the physical body, its primary emphasis are on the development and application of energy and power. Therefore, It's major functions are to strengthen the nervous system, immune system, physiologic organs functions, cogitation and mental creativity of the practitioner. Similarly, the dynamic component also improves all of these things, but its main function is to improve one's physical strength and health.