Telegraphy

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Telegraphy is the long-distance transmission of written messages without physical transport of letters. It is a compound term formed from the Greek words tele (τηλε) = far and graphein (γραφειν) = write. Radiotelegraphy or wireless telegraphy transmits messages using radio.

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Terminology

A telegraph is a device for transmitting and receiving messages over long distances, i.e., for telegraphy. The word telegraph alone now generally refers to an electrical telegraph. Wireless telegraphy is also known as "CW", for continuous wave (a carrier modulated by on-off keying), as opposed to the earlier radio technique of using a spark gap.[citation needed]

A telegraph message sent by an electrical telegraph operator or telegrapher using Morse code (or a printing telegraph operator using plain text) was known as a telegram. A cablegram (see cablegram) was a message sent by a submarine telegraph cable,[1] often shortened to a cable or a wire. Later, a Telex was a message sent by a Telex network, a switched network of teleprinters similar to a telephone network.

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