Blood Types:

There are four major types of blood groups: A, B, AB, and O.

In our lab at school, we tested the 4 bloodtypes with Antigen A and Antigen B to test them positively or negatively with each antigen.

Blood group A
If you belong to the blood group A, you have A antigens on the surface of your red blood cells and B antibodies in your blood plasma.

Blood group B
If you belong to the blood group B, you have B antigens on the surface of your red blood cells and A antibodies in your blood plasma.

Blood group AB
If you belong to the blood group AB, you have both A and B antigens on the surface of your red blood cells and no A or B antibodies at all in your blood plasma.

Blood group O
If you belong to the blood group O, you have neither A or B antigens on the surface of your red blood cells but you have both A and B antibodies in your blood plasma.

These four blood types must be viewed very carefully. Some of them can mix, some of them can't. Take Blood Type A and Blood Type B, for example. If you were to mix those, a serious reaction can occur. What happens is the A antigens attack the B antigens and vis versa, causing harm to the blood system in one's body.