Linked from
The 9 pages that link to Blood typing, each with the reason it gives.
SerologyRelated: Antigen–antibody reactions help establish compatibility before transfusion.
Rh blood group systemRelated: Rh typing detects D antigen and informs transfusion compatibility.
Blood bankRelated: Typing identifies major blood-group antigens needed for safe component selection.
HematologyRelated: Compatibility testing prevents dangerous immune reactions during transfusion.
Charles R. DrewRelated: Reliable transfusion systems depended on identifying compatible blood types.