This document summarizes the ABO and Rh blood grouping systems. It discusses key points such as: - The ABO system categorizes blood into 4 main types (A, B, AB, O) based on antigens on red blood cells. - The Rh system further distinguishes blood as either Rh+ or Rh- based on the presence of the D antigen. - Understanding a person's blood type is important for safe blood transfusions and other medical applications. Testing for agglutination determines blood group.