A smart city utilises Internet of Things sensors, actuators and technology to connect various components across the city.  Data derived from everything connected to the network can be utilised to improve the lives of those in the city.

The video below explains the capabilities of smart cities really well;

I see smart cities as a great way of connecting other technologies in order to streamline infrastructures and our everyday lives.  I think that the technology will have to be implemented incrementally in order to ensure that we use the technology to an appropriate extent and that the it is welcomed by residents rather than being a scary unknown.

Sources:

https://www.techrepublic.com/article/smart-cities-the-smart-persons-guide/