Each country defines what is illegal or not by its national legislation. Accordingly, the world of the Internet as a means of communication and exchanging of thoughts between participants who are subject to the corresponding national legislations, does not operate as a deregulate field.

An action that is considered to be illegal outside the Internet has to be considered illegal within Internet as well. Difficulties arise concerning the enforcement of the national legislations in an environment such as the Internet that knows no national boundaries. The definition of offences also differs from one country to another.