Energy Internet integrates small-scale renewable energy systems, electric loads, storage devices, and electric vehicles for effective transaction of power backed by emerging technologies such as Internet of Things, vehicle-to-grid, and blockchain. Its features, such as plug-and-play mechanism, real-time bidirectional flow of energy, information, and money can lead to significant benefits and innovation in electricity production and. The routing or managing of electrical energy is performed through an energy router (ER), synonymous with a communication router, which routes data packets instead of energy packets. In this paper, a holistic review of the energy Internet evolution in terms of the architecture, types of ERs, and the. The Internet of Energy (IoE) or Energy Internet is a futuristic evolution of the electricity system, conceptualized as an energy-sharing network. It improves a reliability of the system, and provides an increased utilization of energy resources by integrating the smart grid with the. In this paper, we first examine and analyze the typical popular definitions of the EI in scientific literature. Based on their definitions, assumptions, scope, and application areas, the papers are then classified into four different groups representing the way in which the papers have approached the.