Multicast (many-to-many or one-to-many distribution) is the term used to define communication where information is sent from one or more points to a set of other points (From one or multiple servers to set of multiple clients). The senders (Servers) and receivers (Clients) are one or more. Multicast streaming delivers data to more than one sources at the same time, create copies only when the links to the multiple destinations split. Most of the time, Multicast is used to speak about IP multicast (used in the Internet TV solutions and streaming media sector).
(How Multicast Streaming Works)