Argument technologies started a few decades ago as a sub-field of Artificial Intelligence, in which philosophical theories of arguments were leveraged to handle key computational challenges, such as the modelling of non-monotonic reasoning and the design of robust coordination protocols among large numbers of autonomous agents. This soon led to several theoretical breakthroughs, which in turn fostered the development of argument-based applications in a variety of domains, e.g., education, healthcare, policy making, and risk management. As a result, argument technologies have now become a thriving interdisciplinary enterprise, with its own variety of sub-fields and methodologies. This volume offers an updated overview of the current state-of-the-art in this research area, looking at both novel theoretical insights (Part I), new applications specifically tailored for the Social Web (Part II), and innovative tools designed to serve key purposes in various domains (Part III).