Invisible ink, also known as security ink, is a substance used for writing, which is invisible either on application or soon thereafter, and which later on can be made visible by some means. Invisible ink is one form of steganography, and it has been used in espionage. Other uses include anti-counterfeiting, property marking, hand stamping for readmission, fun children's games, and marking for the purpose of identification in manufacturing.
Read more about Invisible Ink: Application and Use, Properties of An "ideal" Invisible Ink, Screening Letters For Secret Messages, Invisible Ink Types, Modern Relevance of Invisible Ink Messages, Digital Invisible Ink
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