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The telegraph is a system for transmitting messages from a distance along a wire, especially one creating signals by making and breaking an electrical connection. -
The telephone is a system of transmitting voices over a distance, using a wire or radio, by converting acoustic vibrations to electrical signals. -
The radio is the transmission and reception of electromagnetic waves of radio frequency, especially those carrying sound messages. -
The television is a system for converting visual images (with sound) into electrical signals, transmitting them by radio or other means, and displaying them electronically on a screen. -
The computer is an electronic device for storing and processing data, typically in binary form, according to instructions given to it in a variable program. -
A tablet is a wireless, portable personal computer with a touchscreen interface. -
The 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.