A Survey on Internet of Things (IoT), Industrial IoT (IIoT) and Industry 4.0

Internet of Things (IoT) is one of the emerging technologies comprises of 'things' capable of identifying, sensing, communicating, processing, and actuating the data gathered from the environment.IoT plays an important role in various sectors including healthcare, medical, education, smart cities, and also it contributes in developing smart industries as part of the industrial revolution 'Industry 4.0' with the use of Industrial Internet of Things (IIoT) technology.This paper provides an in-detail overview of IoT with its functioning, architecture, applications, middleware framework, protocols, and its integration with other key enabling technologies.This paper also provides an overview of the industrial revolutionindustry 1.0 to 4.0 and the Industrial Internet of Things (IIoT) with its applications, architecture, and messaging protocols.Finally, paper covers research challenges in IoT and IIoT.