How do you tell if a US pass port is fake?

To determine if a U.S. passport is fake, examine its physical features, such as the quality of printing, the presence of security elements like the watermark, microprinting, and the color-shifting ink on the cover. Check the passport's data page for consistency in the information and look for irregularities in the photograph or the perforations. Additionally, use a UV light to confirm the presence of the embedded security thread and other features visible only under ultraviolet light. If in doubt, compare it with a verified genuine passport or consult an expert.