Indonesia Energy Transition Outlook (IETO) 2021 is IESR’s annual flagship report which aims to review the development of the energy system in the previous year (2020), outlook the development in the year after (2021) and also track the progress of Indonesia’s energy transition. This year IETO is the fourth time that the report has been published. In its fourth year, IETO has been transformed from previously Indonesia Clean Energy Outlook (ICEO) to reflect IESR’s commitment to support energy transition in the country.  The insights in the report are expected to assist policy makers and society in general to make bold steps in pursuing energy transition and decarbonization for the future.