The notion of
is an important notion in all sciences, each of them studying its own kind of system. Thus physics studies physical systems, biology biosystems, and sociology studies social systems. Since about 1950, research (, , ) has strived for and contributed to the development of a general systems theory, also called
, which focuses on the characteristics of systems across the barriers between scientific disciplines. This systems approach is important for enterprise ontology since we have to deal with at least three distinct kinds of systems: social systems (as will become clear, the essence of enterprises), conceptual systems (information or knowledge systems), and technical systems (ICT systems). Not only is it necessary to profoundly understand these kinds of systems in isolation, but also to understand their interrelationships in a thorough way.