70 ITU‐T's Technical Reports and Specifications Ref. No. Category Definitions/Features Key concept/ Keywords Source 14 Academic The basic feature of a sustainable city can be characterized as: facilitating economical uses of resources by technological and environmental improvements, targeting economic development, wealth building, social progress, and ecological security, maintaining a balance among resources, environment, information, interflow of material of the inner‐outer urban system, meeting a city's future needs based on a correct assessment, and satisfying the present needs of urban development. Technology, economic development, wealth, social progress, resources, information, urban development. Jingzhu (2011c) 15 Academic \"Improving the quality of life in a city, including ecological, cultural, political, institutional, social, and economic components without leaving a burden on future generations\". Ecological, cultural, political, institutional, social and economic. Jingzhu (2011d) 16 Academic World Watch Institute considered that a city moving toward sustainability should improve public health and well‐being, lower its environmental impacts, increase recycling its materials, and use energy with growing efficiency. Public health, materials, recycle, energy efficiency. Jingzhu (2011e) 17 Academic A sustainable city is one that can provide and ensure sustainable welfare for its residents with the capacity of maintaining and improving its ecosystem services. Residents, ecosystem services, welfare. Jingzhu (2011f) 18 Academic The urban ecosystem service can be generally defined as processes and conditions offered for people's survival and development by cities as social‐economic‐natural complex ecosystems. People, survival, development, social, economic, natural. Jingzhu (2011g)