Appeal to authority is adhering to a claim on the basis that the person who said it is an authority figure of some sort. It is not wise to dismiss an expert’s claims when they are speaking about their area of expertise, unless you have equivalent knowledge to think otherwise. However, it would be unreasonable to believe that an authority figure’s opinions must then all be true.
Example: The movie Catch Me If You Can is about a young man who runs away from home amidst his parent’s divorce. In order to sustain himself he becomes a con man, taking on different personas, and making counterfeit checks before he is eventually caught by the FBI. It is an example of this logical fallacy because Frank Abagnale, Jr.’s use of appeal to authority as a fake doctor, lawyer and airline pilot made him credible enough to land him a job in each of these fields without any prior knowledge. All it took was a persuasive personality and a uniform.