OpenAI is preparing to add invisible watermarks to text generated by ChatGPT and Codex in the European Union.

The watermark will not be visible when you read or copy the text. Instead, OpenAI says its new textGrain technology slightly changes the model’s word choices to create a statistical pattern that can later be detected.

“Over the coming weeks, we will add an invisible watermark to eligible ChatGPT and Codex text output in the European Union,” OpenAI explained.