Blood transfusion is the process of transferring blood or blood products into the circulatory system to treat conditions arranged by a doctor. Blood comes from unpaid and voluntary donors in Saudi hospitals and is collected with sterile, single-use equipment. Blood products include red blood cells, platelets, plasma, and more. Blood is typed by groups like A, B, AB, and O, and Rh factor. Tests for diseases like hepatitis, HIV, and syphilis are conducted before transfusion. The transfusion procedure involves verifying the order, preparing equipment, assessing the patient, administering through an IV line while monitoring for reactions, and following policy guidelines.