“A system isn’t just any old collection of things. A system is an interconnected set of elements that is coherently organized in a way that achieves something” Therefore, the system mainly consist of three kinds of things: elements, interconnections, and a function or purpose. (Wright and Meadows, 2012)
Reference:
Wright, D. and Meadows, D. (2012). Thinking in Systems. Hoboken: Taylor and Francis.