AB형 (Blood) is one of the four main blood types in the ABO blood group system, characterized by the presence of both A and B antigens on the surface of red blood cells. Individuals with AB blood type can receive blood from any ABO type, making them universal recipients. This unique trait is important in blood transfusions and organ transplants. People with AB형 blood can donate to other AB individuals but can only receive from AB, A, B, and O types. This blood type is relatively rare, occurring in about 4% of the global population, and is often studied in relation to genetics and health conditions.