 The climate crisis is causing power grids to transition towards more sustainable energy sources such as renewable energy sources, REZs, energy storage systems, ESSs, and virtual power plants, VPPs. VPPs are an emerging concept that integrates distributed energy resources, DRS, and loads to balance electricity supply and demand in real time. They can also participate in energy markets, self-schedule REZs, facilitate energy trading and sharing, and provide demand-side frequency control ancillary services, DFCS, to improve the stability of the system frequency. Studies on VPPs have become increasingly popular due to their potential to reduce uncertainty caused by REZs distributed in the power grid and improved technology related to energy management system, EMS. However, there is currently limited comprehensive research available on VPPs, which makes it difficult to understand how they work and what their potential benefits are. This paper provides a detailed overview of current VPP technologies, including their formation, control techniques, and DFCS capabilities. It discusses the economic, social, and environmental benefits of VPPs, as well as the technological advances, challenges, and possible future. This article was authored by Jechi Liu, Hongjie Hu, Samson SU, and others. We are article.tv, links in the description below.