Not everyone has the same blood type. Blood type refers to features of the person’s red blood cells. There are hundreds of these different features. In general, Rh negative blood is given to Rh-negative patients, and Rh positive blood or Rh negative blood may be given to Rh positive patients. The universal red cell donor has Type O negative blood type. The universal plasma donor has Type AB blood type. The ABO blood groups are the features most people know about. In this group, there are 4 different types of red blood cells — A, B, AB, and O.