This paper proposes a general, yet useful theory of information systems. It is a response to repeated lamentations and debates about whether it is possible to find a set of core concepts for the IS field. Business and IT professionals can apply this theory for understanding and analyzing information systems. Academic researchers can apply it for gaining a deeper appreciation of past research and for developing future research projects. This theory tries to be equally applicable to all information systems, and not just to a particular type of application such as TPS, MIS, DSS, EIS, GSS, or ERP. It also tries to be equally applicable to information systems of today, of 20 years ago, and of the near term