A router joins multiple wired or wireless networks together, via a physical device.  While a router is a special type of gateway, it should not be confused with the term.  A gateway interfaces other networks that utilize different protocols, which is separate from the function of a router.  A router is a Layer 3 gateway, which means that router connects networks and that it operates at the network layer of the OSI model.

Commercial routers are much more powerful forms of routers.  They are used by businesses, hospitals, or universities, for instance, to offer a more comprehensive connection to the Internet, files, and printing systems.  They are normally connected to a wide area network (WAN).  It connects the WAN to a local area network (LAN) that can be in another building across town.  It is also possible for multiple LANs to connect to the WAN with the use of more than one router.

Consumer routers are appropriate for home businesses or the home.  These routers, which can be found at a local electronics store, serve as a wireless access point (WAP).  This provides the access.  Additionally, it serves as a network switch, which tends to be faster than those that are not.  The market for consumer routers varies highly in price range and technology.

The first router that was seen, at least in function, was the Interface Message Processor (IMP).  These devices made up the first packet switching network, which was known as the ARPANET.  This initiated the idea for the router from researchers, where it was known as a gateway, which helps to explain the similarities and common confusion of these two terms.