A broadcast IP packet is delivered to all accessable hosts. Broadcast IP is used for establishing network routing maps (the routers broadcast out messages saying 'I'm here and I know how to talk to these subnets!') allowing routers establish how to reach various sections of the network.
It can also be used for
multimedia transmissions, however you can't use broadcast to stream content at all over the public internet - doing so would involve sending the data to every single system connected to the
internet- and this would obviously be a
huge waste of bandwidth. To avoid this, most routers refuse to forward on broadcasts, limiting multimedia broadcast technology to application where you have complete control over the infrastructure (such as a company's internal
LAN)
See also:
IP Multicast,
IP unicast