The architectural level plays a major role in the engineering of computer based systems. Having proper means for representing the architecture of a system is a crucial element of large system development efforts as it reduces the amount of uncertainty among the involved stakeholders.

This paper presents a systematic approach called FMC (Fundamental Modeling Concepts) to describe the conceptual architecture of software-intensive systems. FMC is a decision-making and planning tool, facilitating the communication between the architect and further stakeholders. We will give a brief overview of FMC and how it can be applied throughout the development life cycle. Finally, we will give some examples of where FMC has been successfully applied in the industry.