Think of it this way, there are three most common types of information transferring methods are: UNICAST: which is the most common type, in which one computer would communicate directly to one client back and forward.
BROADCAST: which consists on one source sending information to all possible destinations, although this method is not too useful because of all the “junk” or unnecessary information that would reach the different destinations.
And lastly MULTICAST: which is essentially like “streaming” all information is sent from one source (the streamer) to all destinations that require it (like the viewers)