Hidradenitis suppurativa (HS) is a complex dermatological disease characterized by recurrent painful nodules and suppuration in areas such as the axilla and groin. The disease is poorly understood and treatment is not satisfactory. In October 2016, the Canadian and United States Hidradenitis Suppurativa Foundations organized the inaugural Symposium on Hidradenitis Suppurativa Advances (SHSA) in Toronto, Canada. This meeting brought together experts from Canada, the United States, and Europe to discuss the latest advances in HS. After this important event, we considered that it would be helpful to outline current HS knowledge and to identify important gaps in treatment and research in order to move forward more efficiently. This paper briefly summarizes current knowledge in key areas including epidemiology, clinical presentation and morphological classification, natural history and prognosis, genotype-phenotype correlations, clinico-pathological correlation, pathogenesis, optimal treatment and outcome measures. General and initial suggestions for addressing these gaps are presented.