A device that converts electronic signals from your PC into sound signals that can be transmitted over a phone line. To receive information the modem works in reverse and converts the sound signals back into digital electronic signals. Modems are used to connect to the Internet or to an online service, such as CompuServe. Some modems are internal and you have to open your PC and fit the modem into a free expansion slot. Most modems are external and plug into the serial port of your PC. Current modems can transfer data at 28,800 bits per second (bps), which is roughly equivalent to one and a half pages of A4 text a second. If you are buying a modem, make sure it has error detection and correction functions called V numbers. You might find it useful to buy a modem that can work as a fax to send and receive text and images to other fax machines. (See also V numbers.)
