Cardiology is unique among medical specialties in three respects. First, it is the largest of all of the specialties. Cardiovascular disease is the most common cause of mortality and serious morbidity, being responsible for more than 40% of all deaths in the industrially developed nations, and the incidence is now rising rapidly in developing countries as well. Second, advances have been more rapid in cardiology than in the other medical specialties. All aspects of cardiology – prevention, diagnosis, pharmacological and invasive therapy – have progressed at dizzying speeds during the past 20 years. Finally, cardiology is the clinical specialty that is most dependent on visual recognition. Beginning with the introduction of the electrocardiogram and chest roentgenogram at the turn of the 20th century to the development of a variety of sophisticated non-invasive techniques as we turn into the 21st century, the practice of cardiovascular medicine has always required the recognition of graphic waveforms and visual images.