Every term here comes with the calculation behind it, a labelled worked example, and the errors that most often make the metric misleading.
AI visibility is the degree to which a brand is mentioned, cited or recommended inside answers generated by AI systems such as ChatGPT, Perplexity, Gemini and Google AI Overviews. It is a sampled rate rather than a position, because the same question can produce different answers on two consecutive runs.
Citation rate is the share of sampled answers that cite your own domain as a source. It separates being talked about from being used as the evidence behind the answer.
Grounding is the practice of generating an AI answer from documents retrieved at query time instead of from the model's trained-in memory. A grounded answer can cite what it used; an ungrounded one is reciting whatever the model absorbed during training.
Mention rate is the share of valid, sampled AI answers in which a brand is mentioned at all. It is the base rate of AI visibility: before position, sentiment or citations mean anything, the brand has to appear.
Prompt coverage is the share of tracked prompts in which a brand appeared at least once across the sampled answers. It measures breadth: how much of your question space you show up in at all.
Share of voice in AI answers is the proportion of brand mentions among all tracked brands — yours plus the competitors you named — across the sampled answers. It answers "when this category comes up, how much of the airtime is ours?" rather than "how often are we mentioned?".
