As machine-generated text and images become common, telling them apart from human work grows harder. Watermarking embeds a subtle, deliberate pattern in the output, imperceptible to a reader but detectable by a matching tool, to mark that it came from a model.
The technique is promising but fragile: edits, paraphrasing or re-compression can weaken or remove the mark, and only the issuing system can reliably detect its own. It is a useful signal rather than a guarantee, and it works best alongside other forms of provenance.