International Investment Law is a complex and evolving field of law that governs foreign direct investment (FDI) and protects the rights of investors across international borders. It is primarily structured around bilateral investment treaties (BITs), multilateral agreements, and various international arbitration mechanisms, such as those provided by the International Centre for Settlement of Investment Disputes (ICSID). The primary goal of international investment law is to create a stable, predictable, and secure environment for investors, fostering cross-border economic activities. It aims to balance the interests of investors and host states, ensuring that investments are protected from unjust expropriation, unfair treatment, and discrimination, while allowing host states to regulate in the public interest, such as in matters of health, environment, and public welfare. Key principles include national treatment, most-favored-nation treatment, fair and equitable treatment, and full protection and security. Dispute resolution is a critical component, often handled through arbitration rather than domestic courts, providing an impartial forum for resolving conflicts between investors and states. This book attempts to understand the critical aspects that fall under the discipline of international investment law and how such aspects have practical applications. It is compiled in such a manner, that it will provide in-depth knowledge about the theory and practice of international investment law. This textbook will serve as a reference to a broad spectrum of readers.