A blood transfusion is a medical procedure that involves transferring blood or blood components from one person to another. This is often done to replace lost blood due to surgery, injury, or medical conditions like anemia. The donated blood is carefully matched to the recipient's blood type to prevent complications. During the procedure, the donor's blood is collected and stored in a sterile bag. It is then infused into the recipient's bloodstream through an intravenous (IV) line. Blood transfusions can be lifesaving and are commonly used in hospitals to treat patients in need of additional blood supply.