ITU‐T's Technical Reports and Specifications 827 performance indicators in smart sustainable cities\", \"Key performance indicators related to the use of information and communication technology in smart sustainable cities\", and \"Key performance indicators related to the sustainability impacts of information and communication technology in smart sustainable cities\"). A comparative analysis of nineteen different index sets is summarized in Table 1. As per the objectives and the scope of this Technical Report, supplementary information on each of the approaches reviewed is presented in the annexes, providing a comprehensive background of the resources that formed the FG‐SSC KPIs series. In order to ensure the inclusion of a wide array of perspectives, the indexes reviewed originate from five different sources: international sources, national/regional sources, city organization sources, academic sources, and company sources, as follows: International sources: a) The International Organization for Standardization (ISO), smart community infrastructures (Annex A); b) The International Telecommunication Union (ITU), ICT development index (IDI) (Annex B); c) UN‐Habitat, city prosperity index (Annex C). National/regional sources: d) China Institute of Communications, evaluation index system of a smart City (Annex D); e) China, Ministry of Housing and Urban‐Rural Development (MOHURD), index system of a pilot smart city (Annex E); f) European Union, European common indicators (EU research initiative \"Towards a local sustainability profile\") (Annex F); g) Italy, smart city and smart statistics (Annex G); h) Japan, Sub working group for SSC of the Telecommunication Technology Committee, index system of SSC (Annex H). City organization sources: i) Global city indicators facility, global city indicators (Annex I); j) International Council for Local Environmental Initiatives (ICLEI), global protocol for community scale greenhouse gas (GHG) emissions (GPC) (Annex J); k) Inter‐American Development Bank, indicators of the emerging and sustainable cities initiative (ESCI) (Annex K). Academic sources: l) Centre of Regional Science (SRF), Vienna University of Technology, European smart cities, ranking of European medium‐sized cities (Annex L); m) Leibnitz Institute, European system of social indicators (Annex M); n) Boyd Cohen, Smart Cities Wheel (Annex N).