Karl Landsteiner was born June 14, 1868, and since he discovered the major groups in human blood in 1901, World Blood Donor Day is celebrated on his birthday. This is also the achievement for which he won the Nobel Prize for Physiology or Medicine in 1930.
Though Karl Landsteiner's paper in 1901 identified the ABC blood types, which was later renamed O. In 1902, AB was discovered by his students, Adriano Sturli and Alfred von Decastello, though they referred to it as 'no particular type'. The new terms were assigned in 1910 by Ludwik Hirszfeld and Emil Freiherr von Dungern, who also explained the genetic inheritance of one's blood type.