[en] Established in 2001, the Generation IV International Forum (GIF) was created as a co-operative international endeavour seeking to develop the research necessary to test the feasibility and performance of fourth generation nuclear systems, and to make them available for industrial deployment by 2030. The GIF brings together 13 countries (Argentina, Australia, Brazil, Canada, China, France, Japan, Korea, Russia, South Africa, Switzerland, the United Kingdom and the United States), as well as Euratom - representing the 28 European Union members - to co-ordinate research and development on these systems. The GIF has selected six reactor technologies for further research and development: the gas-cooled fast reactor (GFR), the lead-cooled fast reactor (LFR), the molten salt reactor (MSR), the sodium-cooled fast reactor (SFR), the supercritical-water-cooled reactor (SCWR) and the very-high-temperature reactor (VHTR). This thirteenth edition of the Generation IV International Forum (GIF) Annual Report covers 2020. In 2020, the GIF, as have all, had to adapt its way of working to the worldwide COVID-19 pandemic situation. In the face of this, all GIF members made their best efforts to produce deliverables and fulfil their objectives in an optimized manner. In 2020 the GIF organization started its transition towards a new communications approach through a rebranding of its logo and web site. This transitional phase will lead the Generation IV International Forum to a new approach in line with the current situation: more virtual meetings and exchanges; a powerful and updated GIF web site to ease and simplify interactions between members; and regular communication through high standard monthly webinars and newsletters. Thus the GIF is ready to enter its third decade of existence in the particular context of a new energy paradigm and an unpredictable sanitary situation. Content: 1 - GIF membership, organization and R and D collaboration; 2 - Highlights from the year; 3 - Country reports: Australia, Canada, People's Republic of China, Euratom, France, Japan, Korea, Russian Federation, South Africa, Switzerland, United Kingdom, United States; 4 - System reports: Gas-cooled fast reactor, Lead-cooled fast reactor, Molten salt reactor, Supercritical water reactor, Sodium-cooled fast reactor, Very-high-temperature reactor; 5 - Methodology working groups: Economic Modelling Working Group, Education and Training Working Group, Proliferation Resistance and Physical Protection Methodology Working Group, Risk and Safety Working Group; 6 - Task force reports: Advanced Manufacturing and Material Engineering Task Force, Research and Development Infrastructure Task Force; 7 - Market and industry perspectives and the GIF Senior Industry: Advisory Panel report, Market issues, Senior Industry Advisory Panel report; A1 - List of abbreviations and acronyms; A2 - Selection of GIF publications (2020).