In the age of multimedia and high-speed networks, multicast is one of the mechanisms by which the power of the Internet can be further harnessed in an efficient manner. It has been increasingly used by various continuous media applications such as teleconferencing, distance learning, and voice & video transmission. Compared with unicast and broadcast, multicast can save network bandwidth and make transmission more efficient. In this seminars, we will review the history of the multicast, present you several existing multicast routing algorithms and analysis the features of the existing Multicast routing protocols that have been proposed for best effort multicast. Some of the issues and open problems related to multicast implementation and deployment are discussed as well.