Table 1 Definitions of smart city and the differences and similarities between them

“Smart city is a very broad concept, which includes not only physical infrastructure but also human and social factors” [16].

Included the social aspects and agreed that smart city has a broad focus.

“The concept of Smart City (SC) as a means to enhance the life quality of citizen has been gaining increasing importance in the agendas of policy makers. However, a shared definition of SC is not available and it is hard to identify common global trends” [12].

Policy makers are an additional aspect of the smart city definition. Consents to the lack of a shared definition of smart cities.

“Smart city, the important strategy of IBM, mainly focuses on applying the next-generation information technology to all walks of life, embedding sensors and equipment to hospitals, power grids, railways, bridges, tunnels, roads, buildings, water systems, dams, oil and gas pipelines and other objects in every corner of the world, and forming the “Internet of Things” via the Internet” [21].

Address the technological aspect of smart cities and focuses on how next-generation information technology is the key.

“A city well performing in a forward-looking way in economy, people, governance, mobility, environment, and living, built on the smart combination of endowments and activities of self-decisive, independent, and aware citizens” [24].

Views a smart city as a futuristic model of collaborative components.

“A city that monitors and integrates conditions of all of its critical infrastructures, including roads, bridges, tunnels, rails, subways, airports, seaports, communications, water, power, even major buildings, can better optimize its resources, plan its preventive maintenance activities, and monitor security aspects while maximizing services to its citizens” [3].

Focuses on the integration of infrastructure and systems that monitor and control the resources to achieve sustainability as the main aspect of a smart city.

“Connecting the physical infrastructure, the IT infrastructure, the social infrastructure, and the business infrastructure to leverage the collective intelligence of the city” [24].

A more generic view that puts together all main aspects of a smart city to achieve the goal. Seems to be most comprehensive definition of a smart city.

“A city striving to make itself “smarter” (more efficient, sustainable, equitable, and livable)” [24].

General definition, does not specify how a city will get smarter.

A smart city is “. . . a city which invests in ICT enhanced governance and participatory processes to define appropriate public service and transportation investments that can ensure sustainable socio-economic development, enhanced quality-of-life, and intelligent management of natural resources” [2].

Views the smart city as specific, and narrow, set of resources/services working together to achieve a better life.