And what is the difference between a router and a switch?

Networking switches (sometimes called "hubs") connect multiple wired network devices to each other. In a business office that has been designed and cabled for multiple users, the network jack in the wall beside each user's desk will eventually connect back to a network switch. Depending on the office's network design and external connection, the switch may connect to a router or to a server acting as a router. In this case, the server will generally act as the office's firewall and Internet gateway.

In a small home office, as previously discussed, the office's router will generally have 4 or 5 wired connections (or "ports"). In this case, the router is acting as a switch for the internal network. But what happens when you have more than 4 devices to connect? In this instance, a small network switch can be connected to the router using one of the wired ports, and additional devices connected to the switch. This works straightforwardly because switches do not have the ability to allocate network addresses, and are therefore part of the same network as the router, simply providing more ports to allow you to connect the devices you need. There are various sizes of switch available - from 4 ports upwards. Should you need help making the right choice for your needs, I'd be happy to advise you.

Des Dougan is Principal of Dougan Consulting Group, which provides technology support services to small businesses in the Metro Vancouver area.  Des has over 30 years experience in the computer business and can be contacted here and via @ddougan on Twitter.