Think of multicasting as the Internet's version of broadcasting. So, for example, any site that multicasts information is similar to a television station that broadcasts its signal. The signal originates from one source, but it can reach everyone in the station's signal area.

Alright, great question! Multicasting uses the same spectrum that is necessary for one analog program but, it allows a broadcast station/s to offer a lot more channels. These extra channels are all digital so this offers more options to the viewer. Ok, hold on, it’s confusing I know so here’s an example:

You’re watching good ol’ analog TV and you’re on channel 12. When you go to change channels, you lose channel 12.

With a digital signal (through “multicasting”) you can view other similar channels (like sports channels) through, yes changing the channel but… when you go to change a channel it would be channel 12-1 and then channel 12-2, 12-3,12-4 and so forth.

Basically this means you get more “viewers choices.” You’ll have more channels of interest to you while remain on the same “channel.” Who would have thought basic TV could get so complicated?