Due to its high association with Raynauds phenomenon systemic sclerosis (SSc) is probably the most common connective tissue disease seen by vascular specialists. In part 1 of our systematic overview we summarize classification concepts of scleroderma disorders, the epidemiologic and genetic burden, the complex pathophysiologic background, and the clinical features and the stage-dependent capillary microscopic features of SSc. Furthermore, we address the diagnostic recommendations propagated by the German Network for Systemic Sclerosis and the Task Force for Diagnosis and Treatment of Pulmonary Hypertension of the European Society of Cardiology, the European Respiratory Society, and the International Society of Heart and Lung Transplantation.