Y-chromosome DNA (Y-DNA) is a type of DNA that is only carried by men and is only inherited from their fathers.
Men who share a common paternal ancestor will have virtually the same Y-DNA, even if that male ancestor lived many generations ago.
All males connected by blue lines have common Y-DNA
Women, on the other hand, do not have Y-DNA. They neither inherit it from their fathers nor pass it down to their sons. In other words, a grandson does not inherit Y-DNA from his mother's father.
Women may still benefit from Y-DNA in their paternal line research when the DNA results of their father or brothers are compared with those of other males.
Please see the sections under Y-chromosome DNA to learn more about different aspects of Y-DNA.