There is no consensus as to what qi is. The upper part of the Chinese character for qi is vapors/steam/breath. Breath as in spirit, which is an energy within our bodies.
The lower part is the character of rice that is being cooked. It is drawn as rice being cooked and popping open. One way to think of it is the result of fuel: Food + Air = Energy. All cells produce qi or energy in the body. This energy or spirit is in all living things.
Qi is also translated as energy and often described as aethereal waves or radioactive emanations. However, these are an overly simplistic translation. Qi animates life and is in every living thing. Balancing or harmonizing qi is important for good health. By managing your qi, you are able live up to your power potential. Having a comprehensive whole-person health therapy is essential.