The paper reviews the potential role of hydrogen and fuel cells in the global energy system, particularly in providing electricity, heat, industry, transport, and energy storage in a low-carbon future. Despite past cycles of high expectations and disillusionment, recent improvements in cost and performance suggest that hydrogen and fuel cells are becoming more economically viable. The review highlights that hydrogen is already established in certain niche markets, such as forklift trucks, and is gaining traction in mainstream applications like fuel cell vehicles and home heating systems. However, challenges remain in terms of cost and performance, and significant improvements are still needed for hydrogen to become fully competitive. The paper also discusses the broader context, including the "lost decade" for hydrogen and fuel cells after high expectations in the 2000s, and the factors enabling the sector to regain momentum, such as technological advancements, commercial availability, and global efforts to mitigate climate change. The review covers various sectors, including transportation, heat production, electricity integration, infrastructure requirements, and policy challenges, providing a comprehensive update on the current status and future prospects of hydrogen and fuel cells.The paper reviews the potential role of hydrogen and fuel cells in the global energy system, particularly in providing electricity, heat, industry, transport, and energy storage in a low-carbon future. Despite past cycles of high expectations and disillusionment, recent improvements in cost and performance suggest that hydrogen and fuel cells are becoming more economically viable. The review highlights that hydrogen is already established in certain niche markets, such as forklift trucks, and is gaining traction in mainstream applications like fuel cell vehicles and home heating systems. However, challenges remain in terms of cost and performance, and significant improvements are still needed for hydrogen to become fully competitive. The paper also discusses the broader context, including the "lost decade" for hydrogen and fuel cells after high expectations in the 2000s, and the factors enabling the sector to regain momentum, such as technological advancements, commercial availability, and global efforts to mitigate climate change. The review covers various sectors, including transportation, heat production, electricity integration, infrastructure requirements, and policy challenges, providing a comprehensive update on the current status and future prospects of hydrogen and fuel cells.