Hidradenitis suppurativa/acne inversa is a diverse, enigmatic and distressful disease that has aroused growing interest in specialists from different disciplines. Both names describe its classical manifestations in the intertriginous regions and reflect the historical view of the disease definition, but cause confusions in the understanding of its pathogenesis and classification. In the light of the advance in clinical, histopathological and pathophysiological findings, we propose the term “dissecting terminal hair folliculitis” (DTHF) to characterize its disease nature as folliculitis instead of acneiform disease or apocrine gland disorder. DTHF attacks exclusively the terminal hair follicles in an overwhelming majority of adults, initiating from the fragile acroinfundibulum leading to a non‐infectious overreaction of innate immunity system with inflammation that may fiercely dissect and engulf all the surrounding tissues accompanied by secondary bacterial infections. Evidence indicates that perifolliculitis capitis abscedens et suffodiens and pilonidal disease are very likely regional variants of DTHF with the same pathogenesis. Treatment of DTHF remains frustrating. The benefit of biologics in targeting inflammation is so far non‐specific, palliative and inconsistent. Hair epilation and photodynamic therapy in treatment of the disease is questionable in consideration of the pathogenesis. Genetic and translational research, especially on the Notch signalling pathways, will yield breakthrough in the development of novel treatment modalities.