Routers, switches and modems are all terms used to refer to the different devices used to connect your computer or other device to the Internet. People use the terms to mean different pieces of equipment when each refers to a piece of equipment that does a specific function. It is not just users that mix up the terms but also the technical people at the Internet providers and their help desks.

Modems were the first devices used to connect computer (which I will use as a broad term to refer to any end device we are connecting to the Internet) and were used to connect your computer to a phone line to the provider. The main thin the modem did was modulate and demodulate the digital signals of the computer to the analog signals on the telephone line with the word modem coming from MOgulate/DEMogulate. The device also served as a router in that it connected your home network (one or more devices) to the Internet provider network.

As we moved to using digital signals on the lines between our house and the Internet provider office, no longer was a modem needed as signals stayed digital (both the line uses digital and the computer uses digital) which increased the speed. However a device was still needed to connect the home network to the Internet provider network. Because we had learned that device as a modem it continues to be called one, but is actually a router. Routers connect networks together. Many of you have simple DSL/Cable routers that only have two connections. One is to the cable (usually a coaxial connection) or a connection to phone line (normal phone plug and the second connection is where your computer plugs in or your switch everyone plugs in plugs in to here

The third device which could be on dialup or cable or DSL connections is a switch. The switch allows a number of our devices to connect together on our network and then has a connection to Internet. The connections could be hard wired or wireless. The switch for home use often has 4 outlets on it for computer cables and wireless for home, but business switches have 8, 20, 40 and 64 outlets on them

Now for the confusing part. You may have a router from your Internet provider that is also a switch which is quite common. It is a router as it connects your network to the Internet provider network and it is also a switch as it has multiple outlets (including possibly wireless) that your computers connect together on your network.