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A telegraph is a system for transmitting messages from a distance along a wire, especially one creating signals by making and breaking an electrical connection. -
A computer is an electonic device for storing and processing data, typically in binary form, acording to instructions given to it in a variable program. -
A telephone is a system for transmitting voices over a distance using wire or radio, by converting acoustic vibrations to electrical signals. -
A raido is a device that either makes, or responds to, radio waves. These waves can travel through materials, like air or wood or glass or concrete, or even through the empty vacuum of space. -
A television is an electronic system of transmitting transient images of fixed or moving objects together with sound over a wire or through space by apparatus that converts light and sound into electrical waves and reconverts them into visible light rays and audible sound -
A tablet is a flat slab ston, clay, or wood, used especially for an inscription. -
A mobile phone is a telephone with access to a cellular radio system so it can be used over a wide area, without a physical connection to a network.