Apart from the Yin-Yang Bagua System, the Five Element (五行) system represents another method Chinese use to categorize and describe the world, but its applicability is pertained to the material (form) part of the world only. The five elements are Metal(金), Wood(木), Water(水), Fire(火), and Earth(土). These five elements are used to describe different parts of the world, and of the human body. For example, in astrology 5 elements are used to describe major plants and star formations in five directions, in medicine 5 elements are used to describe different human organs and body parts.
Apart from general representation, there are two types of interactions between the five elements, i.e. the constructive interaction (相生) and controlling interaction (相克). Based on the specific nature of each element, each element would naturally strengthen one element while control/weaken another. The constructive cycle is: Wood->Fire->Earth->Metal->Water, and the controlling cycle is Wood->Earth->Water->Fire->Metal, represented in the following diagram:
The Five-element system, apart from being used to describe different parts of the world and their interactions, are broadly used in Chinese Medicine (中医) and Fengshui (风水- architecture and interior design). In Chinese Medicine, for example, Daoist believes that bodily health could be achieved when the yin-yang and 5 elements are in balance, while sickness/disease would arise when these elements are off imbalance.