Glossary · Privacy & data
SynthID
Also said as
SynthID-Text
SynthID is Google's system for marking AI-generated content — for text, it nudges which words the model picks so the passage reads normally while a detector can still recognize it.
Why it matters to your business
Gemini already marks its text and Claude started marking its newest models in August 2026, so writing you publish can carry a signal you can't see or switch off — a European disclosure law is what put it there.
The catch · what vendors don't say
Only the company that applied the mark can detect it — you can't check your own text, and a clean result proves nothing, because heavy editing, translation, or an unmarked model washes the signal out. 2026 research on SynthID-style marks found they can also change model behavior under hostile prompting — the scheme does more than pick between synonyms.
