Glossary of Terms
Also called the Landsteiner classification, the ABO blood groups classify blood into four types, A, B, AB, and O, and recognizes which blood groups can be safely mixed. Type O blood can give to all blood types, but can receive only from type O. AB blood type can give to only AB, but can receive from any group. Thus type O is sometimes called the universal donor and type AB the universal recipient. Type A can give to types A and AB and receive only from types A and O, and type B can give to types B and AB, and receive only from type B or O.