BLOOD TYPES

A picture i found on the net with a very helpful and knowledgeable content: (I do not own this picture, fyi. Im just sharing it)

HUMAN BLOOD is grouped into four (4) types: A, B, AB and O. Each letter refers to a kind of antigen, or protein, on the surface of the red blood cells. Antigen is a substance that when introduced into the body stimulates the production of an antibody. Sample antigens are toxins, bacteria, viruses, foreign blood cells and the cells of transplanted organs.