Your printer is tracking youJust as a black spot spells bad news for a pirate (or so we’ve been told by Hollywood – it must be true), so a yellow dot in a laser printer could mean a nefarious user’s activities are under close scrutiny. According to the Electronic Frontier Foundation (EFF) a not-for-profit digital privacy organisation, almost all the major manufacturers of printers have installed invisible yellow dot forensic technology to track the user’s location, time, date, serial number and ID.

A current case in point is NSA contractor Reality Winner, who was traced as the person leaking top secret security material to the media through the printer she used to copy the documents – just as incriminating as leaving her fingerprints.

The unique pattern of yellow dots is invisible to the naked eye but appear when scanned by a blue light or microscope, revealing through a deciphering tool when and where the document originated.