The article discusses the field of sustainability transitions research, which has emerged in the past two decades due to growing scientific and public interest in large-scale societal transformation toward sustainability. It describes three main perspectives in studying transitions: socio-technical, socio-institutional, and socio-ecological. These perspectives explore different types of transitions and provide a basis for theories and models of governance. Common concepts include path dependencies, regimes, niches, experiments, and governance. These concepts have led to three approaches to dealing with agency in transitions: analytical, evaluative, and experimental. The field has developed a broad theoretical and empirical basis, along with various strategies and instruments for social transformation, impacting both scientific fields and policy practice. The article aims to characterize the field by identifying its main perspectives, approaches, and shared concepts, as well as its relevance to real-world sustainability problems and solutions. It also discusses the intellectual origins, emergence, and outreach of transitions research, highlighting its interdisciplinary nature and its role in addressing complex sustainability challenges. The field has grown significantly, with increasing global and heterogeneous research, and has been adopted by various international organizations and programs. The article outlines the core concepts of transitions, including nonlinearity, multilevel dynamics, coevolution, emergence, and variation and selection. It also describes different approaches in transitions research, including the socio-technical, socio-institutional, and socio-ecological approaches, each with its own focus and methods. The article emphasizes the importance of governance in transitions research, highlighting the need for multi-actor dynamics, reframing the problem, visioning, experimenting, and learning and evaluating. It concludes by discussing the challenges and prospects of transitions research in addressing grand societal challenges.The article discusses the field of sustainability transitions research, which has emerged in the past two decades due to growing scientific and public interest in large-scale societal transformation toward sustainability. It describes three main perspectives in studying transitions: socio-technical, socio-institutional, and socio-ecological. These perspectives explore different types of transitions and provide a basis for theories and models of governance. Common concepts include path dependencies, regimes, niches, experiments, and governance. These concepts have led to three approaches to dealing with agency in transitions: analytical, evaluative, and experimental. The field has developed a broad theoretical and empirical basis, along with various strategies and instruments for social transformation, impacting both scientific fields and policy practice. The article aims to characterize the field by identifying its main perspectives, approaches, and shared concepts, as well as its relevance to real-world sustainability problems and solutions. It also discusses the intellectual origins, emergence, and outreach of transitions research, highlighting its interdisciplinary nature and its role in addressing complex sustainability challenges. The field has grown significantly, with increasing global and heterogeneous research, and has been adopted by various international organizations and programs. The article outlines the core concepts of transitions, including nonlinearity, multilevel dynamics, coevolution, emergence, and variation and selection. It also describes different approaches in transitions research, including the socio-technical, socio-institutional, and socio-ecological approaches, each with its own focus and methods. The article emphasizes the importance of governance in transitions research, highlighting the need for multi-actor dynamics, reframing the problem, visioning, experimenting, and learning and evaluating. It concludes by discussing the challenges and prospects of transitions research in addressing grand societal challenges.