Multicast
In plain terms
One-to-many delivery to a group of interested receivers.
Going deeper
Multicast sends a single stream to multiple subscribers efficiently, without duplicating it per recipient. Only interested hosts receive it.
Under the hood
Saves bandwidth for streaming to groups; used in IPTV and within networks, limited on the public internet.
Examples
IPTV, video conferencing, stock tickers, service discovery, streaming.
Think of it like...
Like a radio broadcast only tuned-in listeners receive, sent once but heard by many.