In Traditional Chinese Medicine or TCM, your body is seen as a holistic system. Everything is interconnected and interdependent.
If all of the parts of a system are in harmony with one another, then the whole system is in harmony. If there is disturbance resulting in disharmony, you are likely to see illness, disease and suffering.
This holistic approach to health means one's Chi \ Qi - or vital energy - must flow freely throughout one's body.
Life is essentially a gathering of energies. A healthy and happy human being is a dynamic but harmonious mixture of all the aspects of Chi that make up who we are.
Simply put, Chi is energy - but it's so much deeper than that.
Chi embraces all manifestations of energy, from the most material aspects of energy to the most immaterial aspects.