A router is a networking device which is used today to primarily link a single internet connection with multiple computers on a network. Why is this necessary? Because sometimes an ISP (Internet Service Provider) won’t allow customers to connect more than one PC to their modem and most households today have more than one PC; so if you only have one PC in your home connected to the internet, then the added expense of a router is not for you.
So what exactly does a router do and how does it work? Well a typical router is a wired device with five or more ports for the plugging in of network cables. The smaller routers with just five ports use four to connect the PCs in your home, and the fifth which is usually labeled WAN (Wide Area Network) is where you would plug your modem into the wall to give the computers connected internet access. The router works by giving addresses to the machines connected to it and taking an address from the modem or other internet source connected to the WAN port.
No device on a network can communicate with other machines without an address, called an IP address. When an ISP only allows one PC to be connected at a time, what they will do is give you a device – usually a modem and set it up to allow you only one IP address.
The router then sits between the modem and the other PCs and takes the single address from the modem, and gives the other PCs on the network a different set of addresses, essentially creating two different networks with two different addresses. The router also mediates between the two networks and any request which is sent from any computer is taken by the router and allowed to pass through to the modem, basically bridging the two networks.
Some persons, who do not know if their ISP will allow more than one address to be given out with the device that they received on signing up, may end up buying another network device such as a SWITCH or HUB. These other devices have two main differences from the router and prove ineffective in cases where the modem only issues one IP address. The first difference is that the SWITCH and the HUB cannot issue additional addresses; they only help in connecting multiple machines via cables. The second difference is that the SWITCH and HUB do not have a separate port for plugging in a modem so if someone purchases a SWITCH or HUB without prior knowledge of their modem’s capabilities the result will be that the modem will handle the issuing of addresses, and once it assigns an address to one of the machines on the network, all the others will have no internet connectivity.
Routers come in different brands and different sizes – meaning the number of ports they have varies and security for a router is unnecessary aside from watching who is plugging in.