This SpringerBrief explores the evolution and potential of energy communities as grassroots, socio-political responses to climate change, highlighting European practices and examining their motivations, challenges, and role in advancing a clean energy transition. Being a ‘zoon politikon’ (a political animal), humankind first developed communities to harvest food, build shelter, and engage in socio-political interactions. Today, the term has evolved into a challenging yet promising concept for climate change mitigation and adaptation. It is widely acknowledged that ‘community-based’ strategies serve as conduits for advancing ‘clean’ and ‘green’ energy, gaining traction among scientists and practitioners alike. This Brief aims to provide a clear picture of the phenomenon by focusing on key European practices and exploring their core insights. What, ultimately, is an energy community, and what motivates its actions? Building on these questions, the Brief highlights current research gaps and offers perspectives on how such communities are emerging despite their inherent complexity and multi-dimensional nature.