Systems are about relationships.
Nodes, relations, network A system is an organization of energy or information consisting of nodes, relations, and a network. A node is any concentration of energy or information. A relation is a flow of energy or information between two or more nodes. A network is the set of relations and nodes of a given system. For practical purposes systems can sometimes be treated independently, but in terms of the ultimate energy flow that is the basis of all systems, all systems are interconnected and interdependent.