Networks also support broadcasting. When data is broadcast, a single copy of the data is sent to all clients on the network. When the same data needs to be sent to only a portion of the clients on the network, both of these methods waste network bandwidth. Unicast wastes bandwidth by sending multiple copies of the data. Broadcast wastes bandwidth by sending the data to the whole network whether or not the data is wanted.
Broadcasting can also needlessly slow the performance of client machines.
Each client must process the broadcast data whether or not the broadcast is of interest. Multicasting takes the strengths of both of these approaches and avoids their weaknesses. Multicasting sends a single copy of the data to those clients who request it. Multiple copies of data are not sent across the network, nor is data sent to clients who do not want it. Multicasting allows the deployment of multimedia applications on the network while minimizing their demand for bandwidth.