Systems ensure that a process or several processes deliver the required business results every time. Apply a continuous improvement tool to your business model and the system/s get better, more reliable and increase peoples trust and reliance on the system/s to deliver to plan.

Simple
Four key processes linked together to form a system.

Typical
A series of activities or actions that need to happen at a certain time for the system to be successful.

Complex
Many parts coming together to deliver complex business requirements.
System definition – A system is a group of interacting or interrelated entities that form a unified whole. A system is delineated by its spatial and temporal boundaries, surrounded and influenced by its environment, described by its structure and purpose and expressed in its functioning.
System – Wikipediaen.wikipedia.org

