What is Qigong
The word Qigong (pronounced chi kung) is a combination of two ideas: Qi means air, breath of life, or vital energy of the body, and gong means the skill of working with, or cultivating, self-discipline and achievement. The art of Qigong consists primarily of meditation, relaxation, physical movement, mind-body integration, and breathing exercises. Practitioners of Qigong develop an awareness of qi sensations (energy) in their body and use their mind to guide the Qi.
Qigong provides the practitioner with a great tool for knowledge and health, both for himself and for others, from the point of view of personal practice and of therapy: it promotes the development of a more subtle and powerful awareness of Qi. When Qi is consciously directed in ones own body or that of another, it helps to heal by eliminating blocks, stagnation and weak points in the network of vessels and channels which make up the energy system. The exercises practiced provide a conscious directing of the vital force which can be directed in every cell of ones body, or projected externally through hands, eyes and the mind towards another individual, until it becomes a true conscious pranic-healing: a therapy characterized by the ability to harmonize and heal.

Qigong, and the internal arts can generally be divided into three aspects:

Martial/Movement Arts
Medical
Spiritual

All styles, no matter what the goal of the exercise is, have three things in common:

Posture (whether moving or stationary)
Breathing Techniques
Mental Focus, or Intent