Your blood type is determind of two blood groups: ABO and Rh.
Blood types are Consists of antigens on the surface of your red blood cells. An antigen is a substance that triggers an immune response by your body against that substance.
The presence of specific antigens designates ABO blood types:
Type A has the A antigen
Type B has the B antigen
Type AB has both the A and B antigen
Type O has neither the A nor B antigen
Once your ABO blood type has been determined, it can be further defined by identifying the Rhesus (Rh) factor:
Rh-positive. If you have Rh antigens on the surface of your red blood cells, you have Rh-positive blood.
Rh-negative. If you don’t have Rh antigens on the surface of your red blood cells, you have Rh-negative blood.
By including the Rh factor, the 8 most prevalent blood types can be identified: A+ or A-, B+ or B-, AB+ or AB-, and O+ or O-.