A modem is a device that allows your computer or other devices to connect to the internet over a telephone or cable line.

Think of a modem as a translator between your computer and the internet. When you connect your computer to the modem, the modem communicates with your internet service provider (ISP) over a phone or cable line. It translates the digital signals from your computer into signals that can be transmitted over the line. Similarly, when data is sent back to your computer from the internet, the modem translates the signals into a format your computer can understand.

Modems come in various types, depending on the type of connection you have. For example, if you have a traditional phone line connection, you might use a DSL modem, while if you have a cable internet connection, you might use a cable modem. The router supplied by your internet service provider will have a built-in modem.