This book offers a historical review of the characterization of a disease: the current understanding of pulmonary hypertension and the accumulation of related knowledge dating back to the beginning of the 20th century. From the first reports on pulmonary hypertension at the beginning of the 20th century, to the epidemic of pulmonary arterial hypertension associated with anorexigens that occurred in the 1960s. From the inception of state of the art diagnosis, evaluation, and treatment of patients with pulmonary arterial hypertension to the host of protocols drawn up by the international scientific community. The impact of the disease on the limitation of physical activity and on the lives of those affected is reviewed and addressed in a comprehensive manner, in addition to its hemodynamic components. Finally, the multidisciplinary clinical and therapeutic practice of managing pulmonary hypertension is addressed, towards an understanding of the clinical and functional heterogeneity of patients.