IoT plays a very beneficial role to make the city SMART. IoT is a concept that is rapidly used in this IT sector. Nowadays IoT is the most useful field in the IT sector. IoT- Internet of Things is the network of physical devices, vehicles, home appliances, and other items embedded with electronics, software, sensors, actuators, and connectivity which enable these objects to connect and exchange data. Here we study articles to analyze what is the role of IoT to make a smart city. So we identify that the major role of IoT to make a smart city. The smart city always uses a very efficient environment to establish a network to connect the devices into a system. To make a city smart we use sensors or attached sensors to detect the devices. Arun Kumar says that Nowadays, IoT is rapidly used in this time and have been enormous discussions around building smart cities in India. Sometimes, one questions always in my mind i.e. what really defines a smart city? Imagine a city that acts likes a smart city like a living organism, interacts with you, and continuously fulfilled our needs. A smart city is smart due to its inherent intelligence in dealing with its resources and environment. It makes the effective use of available “ICT”, especially the “IoT”. Here one keyword used-“inherent intelligence”, which means sensors.