|An ad hominem attack is an (counter) argument that attacks a person directly, without addressing the point that was made initially.|
The ad hominem attack is used to counter an unwanted position without going into the details of the argument. It means answering without addressing the point. These arguments are logically fallacious, because they rely on presenting irrelevant information, in an attempt to discredit a certain argument by attacking its source. Though questioning the source of information can certainly be valid in some cases, this type of argument is fallacious in cases where the attack has nothing to do with the discussion at hand, or in cases where the person using it fails to demonstrate how it relates to the discussion.