Historically, Qigong may be seen as divided into six root schools. Here are many types and branches of Qigong:-

Confucian Qigong – explores phenomena towards the attainment of knowledge and the training of one’s morality and Qi
Buddhist Qigong –  seeks unfoldment of the wisdom-energy through a realization of Shunyata (voidness or no-thing), and a deepening of compassion towards all Sentient Beings.
Taoist Qigong – practice without desire, the cultivation of one’s moral character and the seeking of longevity and immortality.
Medical Qigong – aims at strengthening the body and treating and preventing diseases.
Martial Qigong – primarily directed at strengthening and developing of one’s Qi and bodily health in order to aid one’s martial ability.
Folk Qigong – orally transmitted tradition within the confines of a particular family as was, and still is the case with Lohan Qigong.

Although each school possess its own unique method and theory, there remains however, one essential linking element that unites the various school and forms-that of developing one’s Qi or Vital Energy. They also agree that Qigong helps to cultivate the Three Treasures:- Jing (Essence), Qi (Vital Energy) and Shen (Spirit). They share the belief that it can help realize full physical potential, resist sickness, recover damages caused by diseases and balance the body’s energy flow.

All school agreed that the control of respiration plays a central role in the system. The use of breath is a fundamental aspect of Qigong practice, as it is the key to energy control as well as the bridge between the body and the mind. Your lungs themselves cannot bring in and push out air. The muscles around the lungs and the diaphragm must expand and contract, sucking the air into and pushing it out of the chest cavity. This process allows oxygen to mix with the blood in the lung cells, and the blood to release the carbon dioxide it carries. When the diaphragm moves up and down during respiration, it massages the internal organs and increases the circulation of Qi.

Different modes of mouth exhalation can be used to cleanse and stimulate different organs of the body. The systems works by linking the vibratory pitch of the exhalation through the throat and mouth with the frequency of a specific organ-energy system.

It also stress the importance of posture, physical movement, as well as the mind as the main source of Qi flow.

There are many kind of Qi, but they all fall into two basic categories:

Pre-Natal Qi (hereditary), its given to us by our parents and stay with us until we die.

Post-Natal Qi (acquired), comes mainly from the food we eat, the air we breathe and also from the environment in which we live.