The global shift toward decarbonised, decentralised, and digitalised energy systems has positioned microgrids as a key solution for enhancing energy resilience, flexibility, and sustainability. Microgrids—defined as local energy systems integrating distributed energy resources (DERs), storage, and intelligent controls—offer a promising pathway for supplying reliable, cost-effective, and clean energy, especially in areas with high power losses or weak grid connectivity. In Australia, projections by the Australian Energy Market Operator (AEMO) highlight the growing role of DERs, with up to 22% of national electricity consumption expected from these sources by 2040. Microgrids facilitate this integration by operating in both grid-connected and islanded modes, delivering ancillary services and enabling dynamic interactions with the main grid. This book chapter explores the definition, classification, operational modes, and architectures of microgrids, including AC, DC, and hybrid systems. It also outlines a capability review of 30 national and international microgrid projects, extracting lessons learned and best practices in design, control, optimisation, and market participation. The review underpins a research roadmap to address technical, regulatory, and economic challenges, ensuring microgrids contribute effectively to energy system transformation while supporting remote communities and enhancing grid reliability.