#OPSEC365 070/365 Most color printers embed invisible tracking codes on every page. These machine identification codes, also called printer dots, encode the printer's serial number and timestamp on every printout in a pattern invisible to the naked eye. The NSA leaker Reality Winner was caught partly because of these dots. If you're printing something sensitive, know that the printout itself may identify the printer used. Black and white laser printers generally don't include these dots. If you must print anonymously, use a printer you don't own, purchased with cash, from a public location. The EFF maintains a list of printers known to embed tracking codes.