Citation share
Citation share is the fraction of all sources cited across sampled AI answers to a category prompt set that belong to a given site, or to a category of site such as review platforms, communities or competitors. It shows which pages the assistants rely on when they answer questions in a category, and it is the closest thing generative engine optimization has to a ranking report.
Which assistants cite
Perplexity cites on nearly every answer, ChatGPT cites when it searches the web, Gemini often grounds in Google results, and Claude cites when browsing. Google AI Overviews and AI Mode show their sources inline. Coverage differs per engine, so citation share is read per engine as well as overall.
Why it is actionable
Mentions are the score; citations are the why. If one review site is cited in half the answers and your listing there is thin, that is the first task. If a competitor comparison page keeps being cited, you need a better one. The categorized citation list is a to-do list.