Complementary therapy is also known as alternative therapy, alternative medicine, holistic therapy and traditional medicine. A wide variety of treatments fall under this category of "complementary therapy", with each treatment has it's own unique theory supporting it.
In contrast to modern medicine (conventional medicine), complementary therapies aim to treat the the whole person, both body and mind. It works on the belief that the body and the mind is connected and that one cannot be separated from the other. All complementary treatments takes the body as a whole into consideration and aims to utilise the body's own healing mechanism.
Modern medicine, on the other hand, evolved from the belief that the mind and the body are separate. Disease and illness were seen as a mechanical breakdown and only the symptoms thereof were treated. We owe a lot to modern medicine, and complementary therapies have now started to be adopted and used by conventional medicine. Complementary therapy is a perfect partner for western medicine, however it should never be used as a stand alone treatment for a medical condition.