Pulmonary hypertension (PH) was first described by the German physician Ernst von Romberg as “sclerosis of the pulmonary arteries” in 1891, and was considered to be a uniformly fatal disease with an expected survival of <3 years [1,2]. However, an explosion of progress over the past 30 years has resulted in tremendous advances in the understanding of the pathobiology and mechanisms of this disease, through which have developed a systematic approach for diagnosis and eight approved therapies for pulmonary arterial hypertension (PAH). This review will focus on current concepts of mechanisms, diagnostic strategies, and treatment approaches for PAH.