This chapter provides a comprehensive overview of the system of international investment law. Given the relevance of arbitral case law in the development of investment law, it offers a first glance at how investment arbitration works. The chapter provides a general overview of the evolution the international standards relating to investment protection. It shows that the need for an international minimum standard was not seen as necessary prior to 1945 because investment existed in the context of colonialism. Efforts were made to ensure that investors were protected from the non-commercial risks associated with foreign direct investment. The relationship between the host State and the foreign investor is characterized by a long-term business relationship. This typically entails entering into long-term agreements, under which the investor is to provide much needed capital in order to explore and exploit the natural resources of the host State. The chapter also presents an overview of this book.