The environment is composed of at least two components, the natural and the human-made one. Nonetheless, the environment is being used to connote the natural environment. Moreover, even though the components of environment exist in a mutual relationship as a mechanism, it is rare to study the components of environment and their system as a mechanism. With such an implication, this paper aims to identify the components of environment and their system. The components of environment can be categorized by two criteria. One is the subject of creating environment, and the other is the visuality of environment. The former categorizes the environment into the natural and the human-made one, and the latter into physical and nonphysical one. Integrating the two criteria into a framework, the environment can be categorized into the natural, the human-made physical, and the human-made nonphysical environment. The three categories of environment exist interrelatedly in a mechanism being characterized as a mutual impact. The mechanism may be called the environmental system. The environmental system can be analyzed in terms of two dimensions. One is a human-inclusive system. The other is a human-centered system. The former is a framework that includes humans as a component of environment. The latter is a framework that humans are the subject of the environment, and the others surrounding human life are the object of the environment. The former is defined as a circular system of material and energy, while the latter is defined as a mutual subjective-objective system.