The Compendium, like an encyclopedia, contains entries for most of the foundational principles and concepts underlying arbitration. Each entry takes a holistic view of international arbitration, as they tackle core concepts from both a commercial and an investment arbitration perspective, focusing on the fundamental issues underlying the various topics rather than on the solutions adopted in any particular jurisdiction, thus making the Compendium a truly cross-border, transnational resource. This innovative approach will allow readers to identify the commonalities as well as the differences between commercial and investment arbitration, whether and where cross-fertilization has taken place and what consequences it can have. This approach allows the Compendium to be a tool in promoting the creation of a culture of international arbitration that considers commercial arbitration and investment arbitration as part of a whole but with certain distinct features particular to each.