A Rh positive refers to the presence of the Rh factor, a specific protein found on the surface of red blood cells. If a person has this protein, they are classified as Rh positive, while those without it are Rh negative. This classification is important in blood transfusions and pregnancy, as mismatched Rh types can lead to complications. The Rh factor is inherited from parents and is one of the key components of blood typing, along with the ABO blood group system. Knowing whether someone is Rh positive or negative helps ensure safe medical treatments and can prevent potential health issues during pregnancy.