The increasing popularity of electric vehicles (EVs) and the enhanced energy storage capability of batteries have made EVs adjustable resources in economic dispatching for power grids. The guidance and control of discharging EVs have become issues with everincreasing concerns, and the EVs can be discharged to other entities in the grid, which is called vehicle to everything in the power grid (V2eG) technology. When V2eG technologies become widespread, EVs could be widely distributed, fully controllable, and marketable power sources. As ideal mobile power sources, EVs are geographically available all the time. In this paper, the application process of V2eG technology is first introduced, and the current research status of V2eG technology is discussed. The modelling technology involved in V2eG technology is next analysed and discussed in detail. Then, the applications of V2eG technology in economic dispatch are summarized. Furthermore, research on communication technology for V2eG technology is investigated. In addition, the policies and electricity market access criteria related to V2eG are discussed, and the corresponding trading mechanisms are analysed. Finally, the related V2eG technologies are summarized, and the future development direction of V2eG technology is prospected.