The Rh blood group system is a classification of blood based on the presence or absence of the Rh factor, a specific protein found on the surface of red blood cells. Individuals who have this protein are classified as Rh-positive, while those who do not are Rh-negative. This distinction is important for blood transfusions and pregnancy, as incompatible Rh types can lead to serious health issues. The most common Rh factor is RhD, which is the primary antigen responsible for the Rh blood group system. When an Rh-negative person is exposed to Rh-positive blood, their immune system may produce antibodies against the Rh factor, potentially causing complications in future transfusions or pregnancies. Understanding the Rh blood group system is crucial for safe medical practices.