Printers are watching us - a small interesting article revealing the small fact of using invisible ink to control printing. Now a little history: about twenty years ago, printer manufacturers developed a special technology that allows you to identify non-counterfeit money printed on a conventional printer.
For this, yellow dots are printed on the prints, which cannot be seen with the naked eye. This technology was developed in the laboratory of the famous company XEROX and is still used by all leading printer manufacturers.
If the user does not want to be tracked and informs his printer manufacturer about it, then the latter, in turn, reports this to the secret services, which will later find out the reason why you want to maintain complete confidentiality.