Editing Polybius square (section)

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[[File:Polybius square.png|thumb|The Greek letters of a Polybius square]]
The '''Polybius square''', also known as the '''Polybius checkerboard''', is a device invented by the [[ancient Greeks]] Cleoxenus and Democleitus, and made famous by the [[historian]] and scholar [[Polybius]].<ref name=":1">{{Cite web|url=https://penelope.uchicago.edu/Thayer/E/Roman/Texts/Polybius/10*.html#45.6|title=Polybius • Histories — Book 10|website=penelope.uchicago.edu|access-date=2020-04-13}}</ref> The device is used for [[transposition cipher#Fractionation|fractionating]] [[plaintext]] characters so that they can be represented by a smaller set of symbols, which is useful for [[telegraphy]], [[steganography]], and [[cryptography]]. The device was originally used for fire signalling, allowing for the coded transmission of any message, not just a finite number of predetermined options as was the convention before.<ref name=":1" />