In one sentence: A watermark is a mark in a picture, video, audio or text that shows where it came from, and it can be visible or hidden.
Why it matters: NIST says a visible watermark that covers only a small part of the content, such as a logo, can easily be edited out. A hidden watermark needs a detector, and can also be removed. So a watermark is a clue, not proof. A missing watermark does not prove that content is real.
One thing to do: When content has an “AI-made” label, treat it as a clue and still check the source.
Related terms: AI-generated content, deepfake, metadata
Checked: 25 Oct 2026.
