A fundamental need of our economies is to understand the invariables, the laws of technological movement, the structure and the forms of the organization of technology in society. This is in order to direct policies of technological, public, and business innovation. This article aims at answering this need with the systematic presentation of the theoretical foundations of the approach of the technological system, and by showing possible operational applications. Theoretical formalizations of technical systems by Gille, Hughes, Simondon..., continuing a long tradition, from the Encyclopédie to the cinema of Reuleaux, and including Mécanologie, will be illustrated in the first part of this paper. A synthesis of the state of the theory according to these contributions will be presented in the second part. This approach will be built upon with the integration of the constructivist conception and of the technological systemic theory. We will conclude with the description of operationalization perspectives for this approach, as well as the development of a technological prospective, seen as the development of technological systemic means for design. JEL Codes: 030, 031, 033, 052