Multicast is group communication where information is addressed to a group of destination computers simultaneously.

IP multicast is a method of sending Internet Protocol data messages to a group of interested receivers in a single transmission. It is often employed for streaming media applications on the Internet and private networks. The method is the IP-specific version of the general concept of multicast networking.

It uses specially reserved multicast address blocks in IPv4 and IPv6.

In IPv6, IP multicast addressing replaces broadcast addressing as implemented in IPv4.