Technically, virtual power plants consists of distributed power resources, controllable loads, and energy storage devices. It consists of a control center (with different functions under various architectures), metering units, and communication systems. It aggregates electric energy resources, solving the problem of managing scattered and irregular power sources. In terms of business model, diverse business models exist like peak-bottom electricity fee policy and demand side response. In terms of market transactions, virtual power plants face challenges due to the need for efficient and reliable power trading, and the need for flexible management of power resources. An electricity market with their access is essential, and they can conduct cross-regional trading with flexible management models. Overall, a virtual power plants is an aggregation of evolving technologies aiming to optimize power management and realize benefits.