Let me make a quick little chart, and then I'll explain. A B \ / AB | O Okay, now for the real answer. So, if you're O, you can give to everyone and recieve from everyone. If you're AB, you can give...
Type A blood can only go to someone that also has type A. There is a protein in type A blood that would cause blood of other types to clump togather if it is mixed with them. Type B can only give to...