What is a Watermark?

A watermark is a security feature incorporated in bank notes, passports, postage stamps and the things like that to prevent counterfeiting. In digital images too some features are included to prevent fraudulent use. In case of blogs the template designers can use this technique to prevent misuse of their designs. In case of paper watermarks there are various techniques to produce the watermark effects. On digital images it all has to be done, well digitally.