A commonly recognized definition for system is "a combination of interacting elements organized to achieve one or more stated purposes" (SEVOCAB 2017). Systems are often associated with man made items such as cars, computers, and software. However, it is important to recognize that man made systems exist for mankind. Therefore, one involved with the design, development or support of a system should always consider the non-material (mankind) elements associated with a system. Some alternative definitions of a system include:
- an integrated set of elements, sub elements or assemblies that accomplish a defined objective. The elements include products (hardware, software, and firmware), processes, people, information, techniques, services and other support elements” (INCOSE 2015).
- a complex whole the function of which depends on its parts and the interactions between these parts (Jackson 2003).
- a set of principles or procedures according to which something is done; an organized scheme or method.
- A set of detailed methods, procedures and routines created to carry out a specific activity, perform a duty, or solve a problem.
- An organized, purposeful structure that consists of interrelated and interdependent elements (components, entities, factors, members, parts etc.). These elements continually influence one another (directly or indirectly) to maintain their activity and the existence of the system, in order to achieve the goal of the system (Web Finance 2018) .
These broader definitions of a system are important when discussing systems engineering as the systems engineer must establish a holistic view of the user and the user's environment in order to deliver and sustain useful systems.
A System of Interest (SOI) is the system or arrangement of systems that is the subject of an analytic or engineering endeavor (SE VOCAB).