A modem is a device that connects your computer to the internet by converting digital signals into a form that can travel through phone lines, cable lines, or fiber optic cables, and then converting the signals back again at the other end.

The name comes from combining two words: modulator and demodulator, which describe what the device does. Your computer speaks in digital language (ones and zeros), but that information needs to be translated to travel long distances. The modem modulates (translates) your computer's digital signals into waves that can zip through cables, then demodulates (translates back) the incoming signals so your computer can understand them.

In the early days of home internet in the 1990s, modems made distinctive screeching and beeping sounds when connecting, like two robots having a conversation. These dial-up modems were painfully slow: downloading a single song could take 15 minutes. Modern cable and fiber modems are thousands of times faster and work silently.

Today's modems often come built into a combo device with a router, which is why many people don't realize they have a modem. That box your parents might need to unplug and restart when the internet stops working? That's probably your modem (or modem-router combo), still doing its essential job of connecting your home to the vast network of the internet.