ABO blood group system
The World Health Organization (WHO) recognizes World Blood Donor Day on 14 June each year to promote blood donation. This is the birthday of Karl Landsteiner, the scientist who discovered the ABO blood group system. The theme of the 2012 World Blood Donor Day campaign, "Every blood donor is a hero" focuses on the idea that everyone can become a hero by giving blood. Based on data reported by 180 countries between 2011 and 2013, the WHO estimated that approximately 112.5 million units of blood were being collected annually.