Microgrids were initially popularized to increase resiliency of real-time electric power systems regarding natural disasters. With the changing electricity industry landscape in recent years associated with cost-effective distributed energy resources (DERs), such as rooftop solar photovoltaic (PV) systems, distributed storage, and increased active demand-side participation, microgrids are finding their place in this landscape as economic transactive agents capable of providing a variety of services to the mutual benefit of the microgrid, the distribution utility, and the power system at large. Presently, microgrids can participate in distribution utility demand response (DR ) and other demand-side programs, provide energy and ancillary services (ASs) to the bulk power system and markets and in some cases provide voltage support and resiliency to neighboring facilities. The emergence of the new distribution system operator (DSO) construct and the transactive energy (TE) paradigm, however, will further enhance a microgrid's capabilities to participate in retail, wholesale, and bilateral markets when operating in a grid-connected mode.