A blood type is a classification of blood based on the presence or absence of certain antigens and antibodies.

Antigens:

Antigens are substances on the surface of red blood cells that can induce an immune response in the recipient’s body.

Antibodies:

Antibodies are proteins in the plasma that recognize and attack foreign substances (antigens) and aid in eliminating them from the body.

ABO Blood Types:

The ABO blood typing system categorizes blood into four main groups: A, B, AB, and O.

Type A:

Red blood cells have A antigens on their surface, and antibodies against B antigens in the plasma.

Type B:

Red blood cells have B antigens on their surface, and antibodies against A antigens in the plasma.

Type AB:

Red blood cells have both A and B antigens on their surface, but no antibodies against A or B antigens in the plasma.

Type O:

Red blood cells have neither A nor B antigens on their surface, but antibodies against both A and B antigens in the plasma.

Rh Factor:

In addition to the ABO system, blood types are also classified based on the presence or absence of the Rh antigen.

Rh Positive:

If red blood cells have the Rh antigen on their surface, the blood type is classified as Rh positive (Rh+).

Rh Negative:

If red blood cells do not have the Rh antigen on their surface, the blood type is classified as Rh negative (Rh-).