Wikipedia has a good article on it, including photos of what the marks look like. They’re practically invisible to the naked eye, getting them to show up usually requires additional steps like taking high quality scans and running them through some color filters, or using a UV light.
From the EFF coverage of it, it sounds like every laser printer probably prints these marks now. I’m not sure if inkjets or other printer types do or not.
Wikipedia has a good article on it, including photos of what the marks look like. They’re practically invisible to the naked eye, getting them to show up usually requires additional steps like taking high quality scans and running them through some color filters, or using a UV light.
From the EFF coverage of it, it sounds like every laser printer probably prints these marks now. I’m not sure if inkjets or other printer types do or not.