What Is a Modem & How Does it Connect to the Internet?

Learn what a modem is from computer expert Yoav Erez in this Howcast video about wireless network technology.


  • Step 1: What is a modem? Understand what a modem is: something the converts a signal from one form to another.
  • Step 2: Dial-up vs. DSL Instead of dial-up modems that converted audio from phones into data understandable by computers, there are cable and DSL modems.
  • Step 3: Familiarize yourself with your modem Get to know the connection portals and signal lights of your modem.


So what is a modem? Basically in a very broad sense of the word, modem is something that converts a signal from one form to another. In the old days, we used to have dial up modems, which converted audio from our phones lines into data that our computers can understand. But today you don't really see those dial up modems around anymore, what you do see is cable modems and DSL modems.

Now, they basically work the same way; they take data that comes in a certain way through the wall usually in a big thick coaxial cable or a phone cable that comes from our phone lines and convert it to data that our computer or router can talk to.

They're pretty simple devices and they're very straight forward. You have all these indicator lights in the front, they kind of tells you if they're working. If you're lucky it will even say so right on the modem. This one for example has a power light that indicates whether it's connected to the wall or not. USB light which is one of the ways that it can interface with your computer, an Ethernet light that is set in a second way can interface with your computer or your router through an Ethernet cable. It kind of looks like this. And then you have a bunch of lights that tell you basically if the modem is sending or receiving data. Sometimes it'll just be one light called data, sometimes it'll be a light called internet. On this particular modem they really divided it into the to send, receive, sync, and ready.

Now, on the back of the modem you have the USB port that connect to the computer, we have an Ethernet port that can be connect also to the computer or to your router. You have power that will give it power on this this thing and then you have a coaxial cable that connects it to the world or to the outside lines that your cable company company provides. If it's a DSL modem, then instead of this little thing, we'll just have a little phone jack that will connect to the phone line and gives us the DSL signal that we need to connect to the internet. So, that's basically what a modem is.

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