Antiforgery ink is a special type of ink that is used to prevent counterfeiting or forgery of important documents, banknotes, and other valuable items. This ink contains special chemical compounds that react to specific chemicals and conditions, making it difficult to replicate or duplicate. It also has unique physical properties, such as the ability to change color or become invisible under certain lighting conditions, making it even more challenging to counterfeit. Antiforgery ink is commonly used in security printing, such as passports, visas, and identity cards, to prevent fraud and protect against identity theft.