ABO Blood Group System

The ABO blood group system classifies human blood into four main types: A, B, AB, and O. This classification is based on the presence of specific antigens (A and B) on the surface of red blood cells. Type A has A antigens, type B has B antigens, type AB has both, and type O has neither. Each blood type can also have a positive or negative Rh factor, indicating another protein's presence. Understanding your blood type is crucial for safe blood transfusions and organ donations, as incompatible blood can cause serious health issues.