Organ transplantation involves surgically removing an organ from one person (the donor) and placing it into another person (the recipient) to replace a damaged or missing organ. Since the 1980s, over 390,000 organs have been transplanted. Organs can be transplanted from living or deceased donors. Transplants between identical twins are called isografts and do not trigger an immune response, while transplants between other individuals of the same species are called allografts. After transplantation, recipients face risks of organ rejection by their immune systems and other potential complications.