Traditionally, watermark is formed when marking paper. It is not printed on the face of paper but in the middle. Therefore, it can present others from forging the paper which watermark has been added.

Gradually, watermark is applied for electronic documents. As is known, along with sharp development of internet, people often share useful material with Word or other documents online. However, some people may steal the documents. So, the original owners need to take measures to protect the...