ABO System

The ABO system is a classification method for human blood types based on the presence or absence of specific antigens and antibodies. There are four main blood types: A, B, AB, and O. Type A has A antigens, type B has B antigens, type AB has both, and type O has neither. Each blood type also has antibodies against the other antigens; for example, type A has anti-B antibodies. This system is crucial for blood transfusions, as receiving incompatible blood can cause serious health issues. It helps ensure safe compatibility between donors and recipients.