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Blood grouping is done on the basis of antigens (antibody generators ) present on the cell membrane surface of red blood cells.  A Grouping typing test process is carried out to find the grouping.

There are many types of blood grouping done.  Common systems are ABO grouping and Rhesus (Rh) grouping based on the corresponding antigens.

In ABO grouping, the classification is done by depending on the glycoprotein coating. The different groups are :

A,  B, AB,  and O.

Group A has the A type Oligosaccharide polymer is present on the red blood cell membrane.  Group B has the B type Oligosaccharide polymer.  Group AB contains both types.  Group O contains neither type. 

There are sub groups in each of the above groups. like A1+, A1-, A2+, A2-, O+, O-,B+, B-, AB+,AB- etc.  

There are 33 different blood grouping systems that are recognized.