Due to the large spread of the Internet, e-commerce systems are getting more and more important as
a new and effective method to distribute, transact, and exploit digital multimedia content. Interactive
applications and graphic user interfaces, digital image, sound and video databases, e-payment systems,
and e-licensing mechanisms are only a minor element of the existing and arising possibilities.
At the same time, intellectual property rights (IPR) protection and management of multimedia content
has gradually become a critical issue.