ABO blood group

In 1901, biologist Karl Landsteiner classified human blood based on the presence or absence of antigens in blood cells called ABO blood groups. There are about 400 types of antigens in the human body. About 30 of them are known. Humans have 21 blood groups based on antigens. ABO blood group is divided into four groups. namely-

1. A group: 23% of blood is A group.
2. B group: 35% of blood is B group.
3. AB Group: 8% of blood is AB group.
4. O group: 34% of blood is O group. (The German word Ohme comes from O meaning zero)