The essay opens with short definitions of multidisciplinarity, interdisciplinarity, indisciplinarity, and transdisciplinarity, and then continues to recount the history of the concept of transdisciplinarity with its subcategories of theoretical, phenomenological, and experimental transdisciplinarity, each essential for a comprehensive approach. Nicolescu then moves on to outline the methodology of transdisciplinarity, which is based on Galileo Galilei’s three axioms in Dialogue on the Great World Systems. The ontological axiom describes the multiple levels of reality, bringing together natural and social systems. The logical axiom encompasses a combination of critical thinking, experimentation, and observation. The epistemological axiom focusses on complexity and universal interdependence. These diverse approaches highlight the importance of integrating different perspectives for addressing complex, real-world problems.