Dedicated commercial routers
Commercial routers are computers specialized to the special-purpose task of routing. Here are several such routers.
1. A modern NetGear residential router. It is representative of the routers in widespread use in homes and small offices, sold in computer and office supply stores. Its primary management interface is via a built-in web server, so customers connect a computer to it in order to perform management, and do so through a web client ("browser") graphically. It connects to an external ethernet data source. If you have a DSL or cable data source, this device cannot connect to it because it understands ethernet signaling, but not DSL or coax cable signalling. In that case you must interpose a device that does understand the signals that arrive at the residence, and can convert them to ethernet signals for connection to this router. Such devices are called DSL or cable "modems," although technically they are not modems (they don't modulate/demodulate).
2. A late-90s commercial dsl router for small business. The primary management interface to the router was via a built-in telnet server, so customers connected a computer to it in order to perform management, and did so through a telnet client on a command-line basis. The manufacturer, FlowPoint, was acquired and is no longer in business.
3. Enterprise class routers differ in scale, connectivity options, and value-add features in areas like security and efficient data aggregation. However in essential main function-- routing-- routers are all doing the same thing from small to large. Enterprise routers come from companies like Cisco, Juniper, Nokia.