220 ITU‐T's Technical Reports and Specifications 1 Introduction 1.1 Background There are several definitions of a city. A city can be classified according to its population density and its level of urbanization. Both variables are related to the human intervention over a populated area. Those areas with high population density appear to be the most heavily modified when compared with their original landscapes. This reflects the intensity of human activities which have taken place in the area. However, defining a city only from a statistical point of view can be misleading. From an economic point of view, the emergence of agglomeration economies causes an increase in productivity and efficiency in a city. Meanwhile, it reduces transportation and communications costs, stimulates the labor division and promotes the development of economies of scale and increasing returns to scale. These agglomeration economies partially explain the process of urbanization, since people move to cities when companies move business there. Historically, this process has been associated with two major structural changes; firstly, the development of the agricultural and industrial sectors and secondly, the expansion of the services sector. Nowadays, the world is facing a third structural advancement with the development and application of the information and communications technology (ICT). In accordance with this development, there have been several novel concepts for cities based on ICT. The reputed sociologist, Manuel Castells, an influential thinker on the changes caused by ICT, developed the idea of an Informational City. This concept is related to the communication flows among a city. It is important to recognize that in order to be part of this ICT based metamorphosis, cities need to incorporate infrastructures that have the capacity to utilize the potential of ICT and combine them with the existing infrastructure (such as building, roads, etc.). For this reason, the \"convergence\" ICT idea is applied to the infrastructure for \"Smart Sustainable Cities (SSC)\". For instance, electricity networks serve as routes outlined to telecommunications transport networks (which also develops with better control on the electrical system using SCADA systems). The use of buildings for the installation of raised elements such as antennas and base stations is also required. Therefore, ICT acts as an enabler to construct SSC with it is intelligent and efficient use of resources being the focus. Consequently using ICTs in SSC results in cost and energy saving, increased economic growth, improved quality of life (QoL), and reduced environmental footprint. A definition of Smart Sustainable Cities is available in deliverable SSC‐0146 \"Agreed definition of a Smart Sustainable City\" of this focus group. 1.2 Stakeholders in SSC Stakeholders refer to the major players involved in SSC establishment and functioning. The classification of these stakeholders is diverse. In particular, the classification of interdependent and standalone stakeholders distinguishes public and private institutions, local and supra‐local entities, as well as commercial and non‐commercial entities. The following diagram1 shows an example of the interrelationships between some key stakeholders. ____________________ 1 Adapted from \"Broadband and Local Government: evaluation of experiences and recommendations\". United Nations (CEPAL). September 2007