Watermark means a translucent design, pattern or symbol created in paper by varying the distribution of fibers within an area of the paper to identify the manufacturer, brand, or customer. It is best seen when held up to a light. A watermark cannot be copied. Also known as Fourdrinier Watermark. See also Fourdrinier, Mould, and Artificial Watermark.
This Watermark feature is effective primarily in document-present situations where the original document can be examined by a trained professional or scanned with a specialized 3-illumination ID scanner and analyzed with adequate forgery detection technology.
Usability in online and mobile onboarding situations is challenging as the examination is made not on the physical document but on a photograph or scanned image of it.
Ref.: https://www.perfectcloud.io/resources/glossary/