Imagine that every time you print a document, it automatically includes a secret code that could be used to identify the printer -- and, potentially, the person who used it. Sounds like something from a spy movie, right?
Unfortunately, this scenario isn't fictional. Most color laser printers and color copiers are designed to print invisible tracking codes across every single printed page of their output. These codes reveal which machine produced a document and, in some cases, when the document was printed or copied.
This is a video tutorial on viewing your printer's secret dots (fingerprints). For the full tutorial on finding out your printer's fingerprint marks, go to Instructables.