. "Telegraphy (from Greek: \u03C4\u1FC6\u03BB\u03B5 tele, \"at a distance\" and \u03B3\u03C1\u03AC\u03C6\u03B5\u03B9\u03BD graphein, \"to write\") is the long-distance transmission of textual/symbolic (as opposed to verbal or audio) messages without the physical exchange of an object bearing the message. Thus semaphore is a method of telegraphy, whereas pigeon post is not.Telegraphy requires that the method used for encoding the message be known to both sender and receiver. Such methods are designed according to the limits of the signalling medium used."@en . . .