The description of antiphospholipid syndrome (APS) is vascular thrombosis and/or pregnancy morbidity occurring in persons with antiphospholipid antibodies (aPL). However, because of an unclear etiopathogenesis and the heterogeneous nature of aPL and of aPL-related clinical manifestations, a single, unambiguous definition of APS does not exist. In this paper, we describe a structured approach to APS, discuss the controversies, and offer descriptions of APS that include: an autoimmune systemic disease with a spectrum of (mostly thrombotic) clinical manifestations, an overdiagnosed disease when aPL is present but has no proven direct causative role in the clinical manifestations, and a disease of controversies that requires clarification of etiology and mechanisms and risk-stratified controlled clinical studies.