Hydrogen technologies are key for achieving a carbon-neutral economy: They offer solutions for the further expansion of renewable energy supplies, climate-neutral industry processes and sustainable mobility. For Germany and Europe alike, they present an opportunity to maintain industrial value creation, expand export opportunities and secure technological sovereignty.  In this book, the Fraunhofer-Gesellschaft presents the knowledge and experience it has acquired along  the entire value chain of the hydrogen economy, encompassing materials and system development, production, system upscaling, energy sector applications, emission-intensive industry processes and mobility, as well as the practical, overarching issues of safety, standardization and service life.