The twelve articles in this special section focus on new and enabling technologies for smart Internet of Things (IoT). IoT supports ubiquitous information exchange and content sharing among smart devices with little or no human intervention, is a key enabler for various applications. Smart IoT cannot be simply regarded as an upgrade of current IoT by just adding to or replacing sensors/actuators/RFID tags in smart devices. It should be redesigned from the physical layer to the application layer in a bottom-up way. While the traditional-sense IoT paradigm, including the present narrowband IoT (NB-IoT) proposal, aims to provide low-rate, short-range, and relatively stationary connections to the wireless sensors and/or RFID tags, the new architecture is expected to support higher data rates, longer communication ranges, and more flexible mobility for smart devices, with the assistance of some new caching, communication, and computing technologies. These also enable smart IoT to be applied to a broader application area including crowdsensing, crowdsourcing, AR/VR, UAV, and so on, to realize smarter cities, grid, and health, and more intelligent transportation systems. Fully utilizing the communication, computing, caching, and security technologies can essentially complement the current development of IoT.The resulting new structure may have a wider application over current infrastructure-based cellular networks and traditional sensor-based networks by adopting all these features.