Today is the birth day of famous physiologist Karl Landsteiner who first distinguished the main blood groups in 1900, which made it possible to save lives of hundreds and thousands of people every year by means of blood transfusion. So, to honour him, his birth day, 14 th June is celebrated worldwide as World Blood Donor Day (WBDD). The event was first celebrated in 2004 and serves to raise awareness of the need for safe blood and blood products,  and to thank blood donors  for their voluntary, life-saving gifts of blood.