Organ transplantation is the process of surgically removing an organ or tissue from one person (the organ donor) and placing it in another person (the recipient). A transplant is needed because the recipient's organ has failed or been damaged by disease or injury. Some of the organs that can be donated include the liver, kidneys, pancreas, bone marrow and heart. Transplantation of human organs or tissues saves many lives and restores essential functions where no alternatives of comparable effectiveness exist.