There are four major blood types. A, B, AB and O. Each of these four types is then classified into two, whether it is Rhesus positive or negative.
A can receive from and donate to A and O.
B can receive from and donate to B and O.
AB can receive from A, B, AB, and O and can donate to only AB (universal recipient).
O can receive only from O and donate to A, B, AB and O (universal donor).
And Rhesus positive only with positive, negative only with negative.
For more information, A is actually genetically can be AA or AO. B is actually BB or BO.
AB is actually AB or BA which are actually the same. O is actually OO.
If we know the blood type genetically from mother and father,
we can predict the blood type of the children by crossing each one of the letter in genetic blood type of father with each one of the letter in genetic blood type of mother.
For example, if father is AO, mother is BO, the children would be AB, AO, BO, and OO. So, the general blood type of children would be AB, A, B and O.
If father is AA, and mother is OO, the children would be, AO, AO, AO and AO. So all the children would have the blood type A.
What is your blood type? :)