AB positive blood type represents a person’s blood type, and the exact term should be AB RH positive blood type. There are two major blood group systems in humans. One blood group system is the ABO blood group system, which classifies human blood types into A, B, AB and O according to the antigens carried on the surface of red blood cells. The other blood group system is called the Rh blood group system, which classifies human blood groups into Rh-positive and Rh-negative blood according to whether they carry RH-related antigens. Therefore, each person’s blood type is a combination of two blood group systems. AB-positive blood, also known as AB Rh-positive blood, is a relatively common blood type, while Rh-negative blood is very rare and is called a rare blood type.