Final answer:
A router is the device that connects two or more networks, such as a LAN and the Internet, using a single ISP connection.
Step-by-step explanation:
The networking device used to connect two or more networks, such as your LAN and the Internet, with a single connection to your ISP is known as a router. Unlike a hub or a switch, which only facilitates communication within the same network, a router directs data packets between different networks. A modem can be incorporated into or connected to the router to modulate and demodulate the signals between the digital data of a computer and the analog signal of a telephone line or cable system. The usage of a router enables the creation of a home network and provides the devices on this network access to the broader Internet, firmly standing as a cornerstone of modern network connectivity.