If a person goes for a blood type check and the lab report shows that the person’s blood type is O in the ABO blood group system and Rh positive in the Rh blood group system, Rh positive means that there is a blood group antigen called Rh on the person’s red blood cells, if there is no such blood group antigen, it is called Rh negative blood group. The ABO blood group system is familiar and of concern to everyone, including type A, type B, type AB and type O. Not many people know about the Rh blood group system, which, like the ABO blood group system, is a blood group classification method. In fact, there are more than 20 ways to classify human blood group systems, only that the two blood group systems above are found to be closely related to diseases. Blood types are inherited from parents and do not change throughout life, and they are passed on to the next generation.