Multicasting digital television technology that gives viewers access to additional local broadcast TV channels.
A single local TV station can now provide multiple channels (e.g. 2.1, 2.1, 2.3, 2.4, etc.) that provides separate programming simultaneously, which is still all free and over-the -air. Each separate digital stream is called a multicast. Almost every major metromolitan TV station already provides this technology to you.
Thanks to digital TV, we can now have two, three, even six channels coming from one station. This magical feat is accomplished by using the broadcast spectrum more efficiently.
Compared with 'old' analog TV, local broadcasters can now send pictures, sound and other information over the public airwaves in smaller packages. The packages are so small, in fact, that your local DTV station can broadcast not just the single channel you've always had, but up to five more.
Muticasting is also sometimes referred to as "multiplexing."