Blood groups

Blood groups are classifications based on the presence of specific markers called antigens on the surface of red blood cells. The most common system is the ABO group, which includes A, B, AB, and O types, depending on which antigens are present. Additionally, the Rh factor (positive or negative) further differentiates blood types. Compatibility for blood transfusions depends on matching these groups to prevent immune reactions. For example, a person with type A blood can receive A or O blood, but not B or AB. Understanding blood groups is essential for safe transfusions, organ transplants, and pregnancy care.