Checking your blood type is determining the type of antigens present on the surface of your red blood cells. The two main blood group systems are the ABO system and the Rh system. The ABO system has four blood groups: A, B, AB, and O. The Rh system has two blood groups: Rh-positive and Rh-negative.
Knowing your blood type is important for several reasons. If you need a blood transfusion, you must receive blood that is compatible with your blood type. Blood typing is also essential for organ transplantation. Organs from a donor with an incompatible blood type will be rejected by the recipient’s body.