Industry 4.0 reflects the fourth step of the technological and production transition, special in that it provides Internet-connected digital networks, including integrated warehouses, companies, demand-driven growth, and just-in-time’ development. The convergence of the Internet of Things (IoT), intelligent cyber physical systems (CPSs), fog and cloud computing frameworks for automated devices, smart houses, and smart communities were included in Industry 4.0. IoT, Industry 4.0’s integral component, needs significant energy because it requires sense, receives, and conveys among billions of devices of essential data. Green IoT envisages the idea of reducing IoT device’s energy use and keeping the atmosphere clean. We first offer a summary of green IoT and then explain protocols, protection, and application. areas in depth, motivated by a sustainable IoT climate.