The understanding on how international law is regulated is essential to be understood. There are many regulations, especially in international sphere that regulate states. This book captures the most fundamental rules on international law that needs to be understood by anyone who wishes to study about international law. The book is divided in three chapters. The first chapter discuss The Statute of the International Court of Justice. In the second chapter, the author describes about The Charter of the International Military Tribunal (Nuremberg Charter). Meanwhile, in the third chapter, the author discusses The Vienna Convention on Diplomatic Relations. In each chapter, there are four parts that assist the understanding of those regulations which are the introduction, substance of the regulation, the importance of the regulation, legal terms identification, and the text of the regulation itself.