Router

The router, at least the common home network device that we usually call a router, is the piece of network hardware that allows communication between your local home network — i.e. your personal computers and other connected devices — and the Internet.

The router used in home and small networks is more accurately called a residential gateway but you'll never see them called that.

How Routers Work

Routers connect a modem — like a fiber, cable, or DSL modem — to other devices to allow communication between those devices and the Internet. Most routers, even wireless routers, usually feature several network ports to connect numerous devices to the Internet simultaneously.

Typically, a router connects physically, via a network cable, to the modem via the 'Internet' or 'WAN' port and then physically, again via a network cable, to the network interface card in whatever wired network devices you may have. A wireless router can connect via various wireless standards to devices that also support the particular standard used.

The IP address assigned to the 'WAN' or 'Internet' connection is a public IP address. The IP address assigned to the 'LAN' or local network connection is a private IP address. The private IP addresses assigned to a router is usually the default gateway for the various devices on the network.

Wireless routers, and wired routers with multiple connections, also act as simple network switches allowing the devices to communicate with each other. For example, several computers connected to a router can be configured to share printers and files amongst themselves