A device that connects multiple networks to allow communication between them is known as a router. Routers direct data packets between various networks and can include local area networks (LANs) and wide area networks (WANs). They handle traffic directing decisions based on IP addresses, ensuring that data reaches the correct destination efficiently. Routers may also provide additional features like firewall protection and network address translation (NAT), enhancing security and optimizing traffic management. In home environments, routers are essential for connecting personal devices to the Internet, facilitating seamless communication.