ITU‐T's Technical Reports and Specifications 73 Ref. No. Category Definitions/Features Key concept/ Keywords Source 26 Academic In general terms, we can define a \"smart city\" as a public administrative service or authority that delivers (or aims to deliver) a set of new generation services and infrastructure, based on information and communication technologies. Defining a new generation service is nevertheless a bit more complex and broader as the systems and services provided by smart cities should be easy to use, efficient, responsive, open and sustainable for the environment. The \"smart city\" concept brings together all the characteristics associated with organizational change, technological, economic and social development of a modern city. Moreover, smart city services and infrastructures entail the characteristics of engaging and interacting with the citizen that makes use of them. Another central element is the adaptive nature of services, ICT systems, infrastructures, buildings that comprehend the smart city concept. They acknowledge their initial status via a set of indicators and adapt their response according to the external changes that affect them. In doing so, they intelligently adapt to the external variables and demands that they are subject to, thus offering an always customized, more efficient and adaptive response. Technology, economic, social development, ICT, infrastructure, buildings. González et al. (2011)