The network card allows computers to send and receive network messages. Messages (or packets) can be broadcasted to all receiving nodes in a subnetwork, or sent to a specific node with a specified address. Relays can be used to bridge multiple subnetworks by relaying messages between the subnetworks they are connected to. It is also possible to send a targeted message if the receiver is in another subnetwork, if the networks are connected via one or more relays.