This video is about Blood Groups. Landsteiner and Veiner describe two systems to identify blood groups. One of them is ABO system and other is Rh system. These systems are based on antigen and antibody activity. According to ABO system four blood groups are present like A, B, AB and O. AB blood group is universal receptor while O is universal donor. Rh factor may be present or absent in blood. If present it is known as positive blood group.