Modem: A modem is a hardware device used to connect computer systems to the Internet or other networks. It is used to convert digital signals from the computer to analog signals that can be sent over telephone lines. Modems can also be used to connect two computers together on a local network.
Router: A router is a hardware device that connects multiple networks together. It is used to route traffic between different networks, such as the Internet and a local network. Routers also provide security features, such as firewalls, and can be used to filter traffic.