A modulator-demodulator, or simply a modem, is a hardware device that converts data from a digital format, intended for communication directly between devices with specialized wiring, into one suitable for a transmission medium such as telephone lines or radio.

Computer Network Terms I

A computer network is a set of computers sharing resources located on or provided by network nodes. The computers use common communication protocols over digital interconnections to communicate with each other. The connections between nodes are established using either physically wired, optical, or wireless radio-frequency that may be arranged in various network topologies. The best-known computer network is the Internet.