An ad hominem argument is one that is used to counter another argument, but it is based on feelings of prejudice (often irrelevant to the argument), rather than facts, reason or logic. It is often a personal attack on one's character rather than an attempt to address the issue at hand. This type of fallacy can often be witnessed in individual debates, in court or in politics. Often, the attack is based on one's social, political, or religious views, or on lifestyle choices of the person being attacked using ad hominem. The result of an ad hom attack can be to undermine someone's case without actually having to engage with it.
These examples of ad hominem arguments show that various forms of verbal attack can be used in this type of argument to appeal to emotion and prejudice. Being aware of how an ad hominem argument works can help us judge when we should ignore its use and when we should consider it appropriate. When might an ad hominem argument be justified? It may be perfectly reasonable when a person's good character or credibility is relevant to the argument.