Originally engineers called it the 'MODulation - DEModulation' box. But it was such a mouthful that naturally they ended up calling it the MODEM.

A modem converts the digital data from the computer into a continuous analogue wave form that the telephone system is designed to deal with (MODulation).  The reason for this is that the telephone system was originally designed for the human voice i.e. continuous signals.  The modem also converts the analogue signal from the telephone network back into digital data that the computer can understand. (DEModulation).

Standard modems come in two forms. An external box that links to your computer either through a serial or USB port, or an internal modem that is plugged directly to the motherboard inside the computer.

An internal Modem

An external modem

Up to quite recent times, modems connected to the standard telephone line at speeds up to 56 kilobits per second. This was OK until broadband became available which offers ten times the speed. However many people still have to use a 56Kb modem to connect to the internet because their local exchange has not been converted to broadband as yet.

Wi-Fi modems

In addition to telephone modems, radio has now become very popular as a means of connecting to the internet. The device that allows you to do this is called the Wi-Fi modem