The term "Grundnorm" refers to a fundamental norm or principle that serves as the foundation for a legal system. Introduced by legal philosopher Hans Kelsen, it represents the highest rule from which all other laws derive their authority. The Grundnorm is not written or codified but is accepted as the ultimate source of legal validity within a jurisdiction. In Kelsen's theory, the Grundnorm helps to maintain the coherence and stability of a legal system. It provides a framework for understanding how laws are created, interpreted, and enforced. This concept is crucial for analyzing the legitimacy of laws and their application in society.