Glatt Plagiarism Services , for example, provides software that lets instructors quickly trace sources of plagiarism by comparing students' texts with numerous free and marketable collections of papers. Instructors at many colleges and universities now routinely use such detection programs. I've heard that it's possible for Web designers and the owners of institutional Web pages to trace illegal copying of copyrighted images, graphics, and music. Yes, it is possible for the owners of online materials to trace illegal copying. By embedding digital watermarks in graphics, images, music, and texts, owners of copyrighted materials can trace the location of illegal downloading.
Several companies provide digital watermarking systems.
These technologies are used in a wide variety of applications, including the deterrence of counterfeiting, piracy and other unauthorized uses. There you will find advice on how to cite online sources in both print and hypertext documents.