Accidents occur nearly everyday. The victims of these accidents sometimes need blood to replace amount they have lost or they may die. Every hospitals has a blood bank where collects, stores, processes, and transfuses blood. The hospitals constantly appeal to those who are healthy to come forward and contribute some blood which is then kept in blood bank. Before blood banks were established, the doctors had to find out the blood type of the patient's relatives and friends until the proper was found. Then he had to perform the cross-match, bleed the donor and then carried out the transfusion. Many new ways of cross-matching were discovered. This led to the setting up of blood banks. Many people believe that if they give blood they will become weak or ill. This is not true. Healthy people have five to six liters of blood in their bodies. Giving away some will not make them feel weak at all. Their bodies will quickly replace the blood that they have given away.