In one sentence
A hallucination is a confident but false statement produced by an AI model. For brands the practical risk is a model inventing pricing, features, policies or comparisons that were never true, and repeating them to buyers as fact.
Brand hallucinations usually have a cause you can fix. The most common is silence: if your site never states a price, a limit or a policy in plain language, the model fills the gap from stale third-party pages or from pattern-matching against competitors.
Monitoring matters here as much as content. You cannot correct an answer you never saw, and the same wrong claim tends to appear across multiple engines once it enters the ecosystem.
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