is a design made by impressing a water coated metal stamp or roll onto paper
during manufacturing. The result is a pale shadowy image that is clearly visible when the paper is held up to the light. Watermarks originally were used to identify paper manufacturers. They were introduced into modern Europe
. They have also been used on postage stamps
and other government documents to prevent counterfeiting
Encoding an identifying code into digitized music, video, picture, or other file is known as a digital watermark.