Within systems theory, a system is the part of the universe that is being studied, while the environment is the remainder of the universe that lies outside the boundaries of the system. All systems have a boundary and operate within an environment. This environment represents the sum total of other systems and input/output resources that the system interacts with during its operation. Thus, the environment consists of the sum total of resources and systems that lie outside of the boundary of the system of interest and interact with it, providing its inputs and receiving its outputs.