Editing Invisible ink (section)

{{Short description|Substance used for writing which is invisible and can later be made visible}}
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{{for|the song|Lorde}}
{{distinguish|Invisible, Inc.}}
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{{More citations needed|date=January 2020}}
[[Image:ArnoldCipherLetter.jpeg|thumb|right|upright=1.3|A coded letter from [[Benedict Arnold]], originally written in invisible ink. Handwriting by [[Peggy Shippen|Peggy Shippen Arnold]] is interspersed with coded communication in Arnold's hand.]]

'''Invisible ink''', also known as '''security ink''' or '''sympathetic ink''', is a substance used for writing, which is invisible either on application or soon thereafter, and can later be made visible by some means, such as [[heat]] or [[ultraviolet]] light. Invisible ink is one form of [[steganography]].