The term "life force" refers to an invisible energy or vitality that is believed to be present in all living things. It represents the driving force behind life, growth and reproduction, and it is often associated with concepts such as qi (in traditional Chinese medicine), prana (in Hinduism) or ki (in Japanese martial arts). In essence, "life force" refers to that mysterious something within living organisms that enables them to maintain their vital functions, resist illnesses and recover from injuries. It is often seen as the animating principle of all life forms, giving them energy, strength and vigor.