54 ITU‐T's Technical Reports and Specifications FG‐SSC has four (4) main working groups (WGs): WG1 – ICT role and roadmap for smart sustainable cities. WG2 – ICT infrastructure. WG3 – Standardization gaps, KPIs and metrics. WG4 – Policy and positioning (communications, liaisons and members). One of the key deliverables for WG1 in the Focus Group on SSC is to develop a standardized definition for smart sustainable cities: \"What definitions and attributes describe a smart sustainable city\" especially in terms of ICT infrastructure. In order to help address the above questions, FG‐SSC has developed this detailed Technical Report on Smart sustainable cities – an Analysis of Definitions. Using this Technical Report as a basis, the Focus Group will be able to fulfil its mandate to develop a set of Draft Technical Specifications for ITU‐T Study Group 5 for a standardized definition of a “smart sustainable city”. 2 Goals and motivation for a comprehensive definition 2.1 Goals With rapid urbanization and the obvious need to develop a sustainable model to support anticipated growth, a number of cities in the world has jumped on the 'Smart Sustainable City' bandwagon labelling itself as 'smart' in one way or the other. The primary goal of this Technical Report is to help understand the multiple definitions of ‘Smart Sustainable Cities’, based on open literature, perform analysis and then propose a formal and comprehensive definition for the ITU term Smart Sustainable City (which specifically highlights the sustainability aspect in such cities). Such a standardized set of terminologies for a \"smart sustainable city\" will be useful not only for the definition of the term but also in relation to ICT infrastructure, KPIs, metrics and policies for smart sustainable cities as viewed by ITU. 2.2 Lack of standardized terminologies Though there is abundant literature available on smart cities, there is no standardized, commonly accepted set of terminologies which would help to aptly describe a \"Smart Sustainable City\". Depending upon the lens with which it is viewed, there are different descriptors, definitions, attributes, indicators and indices. To ensure that the sustainability aspect in smart cities is not overlooked, ITU‐T Focus Group on Smart Sustainable Cities has conceptualized a new term. Smart sustainable cities which may be considered a variant of smart cities (inclusive of some of the basic features of eco‐cities/sustainable cities). Various definitions and features of smart cities and sustainable cities have to be analysed before setting a standardized definition which is expected to provide a good basis for the development of the concept of smart sustainable cities (SSC) for the Focus Group on SSC and its various stakeholders. What could be the main features which make a city a \"smart sustainable city\"? Is it governance, technology, communication, transport, infrastructure, people, economy, environment, natural resources, innovation, quality of living or something more? What are the necessary factors for a city to be called as smart and sustainable?