A router is a computer network device that receives data through one connection and then sends (routes) it to other connections, perhaps making changes to the data as it passes it on.
Most consumer-grade routers are actually fairly simple devices, with a connection to the internet on one “side” (the “outside” or WAN connection), and connections to one or more computers on the other (“inside” or LAN connections). In homes and small businesses, a router is mostly thought of as a way to share one internet connection with multiple computers.
Many consumer-grade routers also include a wireless access point, which is simply a way to connect more computers to the LAN to share the internet connection. Technically, the access point is a separate device, which has simply been included in the same box as the router for convenience. Thus, a “wireless router” is nothing more than a router that happens to have a wireless access point built in.
Think of a router as a small computer that can be programmed to understand, manipulate, and route the data that it is asked to handle. For example, broadband routers include the ability to “hide” computers behind a type of firewall, which involves slightly modifying the data as it traverses the device (referred to as NAT).
All routers include some kind of user interface to configure how the router will treat traffic. Large commercial routers have the equivalent of a full-blown computer programming language to describe how they should operate, and also include the ability to communicate with other routers to describe or determine the best way to get network traffic from point A to point B. Consumer and small business grade routers usually have a simple web-based interface that allows you to control various configuration options, such as IP addressing and security.
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