The present study deals with the concept of "Independent Regulatory Authorities". In the context of this contribution, an approach is attempted to these Authorities, focusing on their European and to the extent possible sectoral dimension. The ARAs that are activated a) in network markets (electronic communications, energy, postal services, railway transport, with the addition of competition authorities responsible for horizontal market supervision), b) in financial and insurance markets (financial supervision, solvency) and c) in the field of fundamental rights protection (radio-television services, personal data processing) are presented. Following the good French traditions and Cartesian logic, the author explains in two tightly bound chapters how these modern forms differ from each other, while developing essential common characteristics. The diversity (Chapter I) is primarily located in issues related to legal personality, degree of independence, powers and control of ARAs. It is interpreted on the basis of the diversity of the powers of each ARA, the regulatory specificity of each sector to be regulated, and the individuality of national legal orders. The points of convergence of ARA regulation (Chapter II) mainly arise from the gradual emergence and substantive safeguarding of their independence, which, however, in order to avoid impunity, is surrounded by a series of "institutional safeguards" of transparency, accountability and control at national and European level, as well as by the creation of networks between national ARAs and by their "vertical" cooperation with the European Commission. The work is accompanied by an alphabetical index of concepts.