428 ITU‐T's Technical Reports and Specifications 1 Introduction For the first time in history, more than 50% of the world's population live in cities1. The projected rates of urban growth will bring benefits and challenges. Demographic and social ecosystems will need to evolve, economies will be under increased pressure, the environment will be challenged, city governance will have to adapt, digital and social inclusion needs will grow, and health care and education provision will demand new approaches, among others. In order to address these challenges, cities need to become, and in many cases are already becoming, 'smart', by ensuring a more rational approach to the way services are operated and delivered, and by aiming at a better and more sustainable quality of life for city inhabitants. ITU‐T Study Group 5 “Environment and Climate Change” and UNECE define a smart sustainable city as \"an innovative city that uses information and communication technologies (ICTs) and other means to improve quality of life, efficiency of urban operation and services, and competitiveness, while ensuring that it meets the needs of present and future generations with respect to economic, social, environmental as well as cultural aspects”. As ICTs are a key enabler of SSC, the systems involved can profit from the ability to be highly interconnected through various technologies. For example, a broad variety of applications will be introduced based on the Internet (e.g. e‐government, e‐commerce, e‐money, online banking), while IoT will be adopted in applications such as intelligent transportation, connected health care, public safety and security, emergency services, smart grid and smart metering and intelligent buildings, among others. In order to guarantee service continuity and integrity, the ICT systems that oversee and control smart and sustainable cities need to consider, from the initial stages of inception and design, measures to ensure cybersecurity, robustness, reliability, privacy, information integrity, and crucially, resilience. 1.1 Scope This Technical Report explores the requirements and challenges involved in creating a secure, reliable and resilient smart sustainable city. It considers how administrations and the overall city ecosystem will need to provide innovative, resilient \"smart\" solutions that leverage digital information while protecting against malicious violations, unintentional damage and natural disasters. The content of this Technical Report is aimed at an audience of SSC stakeholders, including city officials and administrators, among others, described in the Technical Report on SSC Stakeholders. When required, reference is made to other Technical Reports that have been prepared as part of the mandate of ITU‐T Focus Group on Smart Sustainable Cities2. 1 UNFPA (2007), State of the World Population 2007: Unleashing the Potential of Urban Growth, United Nations Population Fund (UNFPA). Available at: http://www.unfpa.org/swp/2007/english/introduction.html. 2 The Technical Reports are available on the website of the ITU‐T Focus Group on Smart Sustainable Cities at: http://www.itu.int/en/ITU‐T/focusgroups/ssc/Pages/default.aspx.