After these two technologies, the Internet followed as the third communication technology, changing the telecommunication world. Though the Internet was initially designed for individual communication, the protocols and mechanisms added at the beginning of the nineties introduced a new communication form: group communication (multicast). Multicast makes possible an efficient data distribution to several receivers. By contrast with the mass communication of (radio) broadcasting, where data is distributed to all participants within one single transmission medium, group communication delivers data units only to those receivers explicitly interested in this data. In addition, group communication in the Internet (IP multicast) enables each Internet computer to send data directly to the members of a multicast group.