AI watermarking adds a hidden pattern to text, images, audio or video as it is generated. People cannot notice it, but a detector that knows the pattern can. For text, the model nudges its word choices in a pattern linked to a secret key.
Google DeepMind’s SynthID is a well-known example, and Google says it is applied to all Genie 4 video and audio. A watermark can confirm content came from a system that uses one, but a missing watermark does not prove a person made something.