A system is a set of interacting parts. Systems can include matter, energy, and information. By grouping a set of related parts or events into a system, scientists and engineers can study how matter and energy behave.
A system can have inputs (things that enter the system) and outputs (things that leave the system). Inputs and outputs can be matter, energy, or information. New matter or energy cannot be created nor destroyed. Instead, matter and energy can only be transformed into new forms or be introduced from outside the system. To accurately model a system, you must understand the inputs and outputs of that system. You also have to understand the flow of matter, energy, and information through the system.
