Tissue regeneration refers to the process by which damaged or lost tissues are replaced and restored back to their normal function. This can occur naturally in some organisms, while others may require medical intervention for successful regeneration. The term is often used specifically when referring to the repair of organs or body parts such as skin, bone, blood vessels, nerves, and muscles. Regenerative medicine aims at promoting tissue regeneration through various therapies and techniques that stimulate the body's own healing mechanisms.