This paper introduces the model of design (MoD), a framework that leverages category theory to study the design and development of computer-driven systems, to the academic and engineering communities dealing with computer systems. The model of design aims to offer a minimal framework for modelling the design and development of embedded computation across domains and abstractions, focusing on functional and extra-functional aspects as well as overarching concerns for automaticity, correctness and reuse. This nuanced approach provides insights into the theory and practice of computer systems design.