Internet Protocol Multicast(ing) - (IP Multicasting) - A multicast sends information to many recipients at once, as opposed to a unicast, which is a transmission directed to a single recipient.  It can be used to videocast media such as news bulletins, stock quotes, weather reports, conferences, etc.

IP Multicast Initiative- (IPMI) - A consortium and forum organized for accelerating the adoption of IP Multicast (an IETF standard).