I know what a router is, it's what I've always used, but what is a switch?

Switch basically a smart hub. You know what a hub is right? Where you basically plug in all your machines, and they get info. Here's how it works.

Hub=Plug in all machines, and the hub shoots the signal to every port on the hub whether something is plugged in or not. In other words, hubs are dumb devices. They are ok if you don't have many machines, but get too many on one, you will start having data collisions, data loss, etc.

Switch=Smart hub, basically the same as a hub, but has a small processor built in, and sends the information only to the port which needs that information, makes for less data collision and less data loss, and higher throughput.

Router is more of a device designed to sit between your network and the outside world, you put a router on say between you and your internet connection, I could have one router, and it uses one IP address, and I could have 20 machines in my house with different IP's on my own personal network, connected to a switch which connects to the router, but all my ISP sees is one IP address, IE, my ISP thinks I only have 1 computer online when I may really have several sharing thanks to the router.

But where the confusion comes in is so many devices are going to all in one style. IE, you buy new wireless router, well it's got your routing hardware obviously, but may also have 4 output ports, and some firewall functionality, as well as be able to serve as a wireless access point all at the same time. See what I'm saying? Essentially you've got like a 3 in one deal, whereas it used to be you'd buy a router, switch/hub, firewall, and wireless access point all seperately. This system is great for a home user, but when you have a larger network, the heavy duty, dedicated stuff is probably preferred. Hope it helps.

Also, a switch gives dedicated bandwidth per port as where a hub shares the bandwidth among all ports. If you ever have to choose between a hub or switch (where price is not an issue), always purchase the switch.

Anyways....a switch passes data using MAC addresses and a router routes traffic using IP addresses.