what is universal donor

A universal donor is a person with a specific blood type that can be given to people of any blood type during a transfusion. The universal donor blood type is O negative. This is because O negative blood does not have any antigens on the surface of the red blood cells that can trigger an immune response in the recipients body. Therefore, it is considered safe to give to anyone, regardless of their blood type. In contrast, people with other blood types have specific antigens on their red blood cells that can cause an immune response if given to someone with a different blood type.