What device is used to connect two or more packet-switched networks or subnetworks?

A router is specifically designed to connect two or more packet-switched networks or subnetworks. It operates at the network layer of the OSI model, using routing tables to determine the best path for forwarding packets between different networks. Routers can handle packets coming from various networks, manage traffic between them, and even provide additional functionalities such as firewall capabilities, network management, and traffic directing based on IP addresses.

In contrast, a hub is a basic networking device that connects multiple computers in a single network segment but does not route traffic between different networks. A switch, while more advanced than a hub, operates mainly at the data link layer and is primarily used to connect devices within the same network. A bridge connects two parts of the same network to help reduce traffic but does not function to connect separate networks independently like a router does. Hence, the router is the most suitable choice for facilitating communication between different packet-switched networks.