What is blood group?

Blood group refers to the classification of blood based on the presence or absence of certain antigens on the surface of red blood cells. The most common blood group system is the ABO system, which categorizes blood into four main groups: A, B, AB, and O. Another important blood group system is the Rh system, which classifies blood as Rh positive or Rh negative. Knowing a person's blood group is important for blood transfusions and organ transplants, as compatibility between donor and recipient blood types is crucial to prevent adverse reactions.