Ad Hominem

Ad hominem is a logical fallacy of attempting to undermine a speaker's argument by attacking the speaker instead of addressing the argument.

An example of ad hominem was in one of the debates between President Obama and Governor Romney. In the debate Governor Romney "attacked" Obama by asking him why he have less ships then we did before when his argument wasn't about Obama but on what he wanted to do about the military situations.

This qualifies as ad hominem because Romney tried attacking Obama by trying to say he was doing something wrong but the question that was supposed to be answered by Romney was how he planned to make the military stronger. That took away from the argument and didn't address the initial questioned that Romney was asked.