What is share of search?
Share of search is a brand's portion of all search volume in its category, calculated by comparing how often people search for that brand's name against searches for the category as a whole.
It predates AI answer engines by years and was popularized as a leading indicator of market share: brands people are actively curious about tend to get searched for by name more often, and that curiosity has been shown to move ahead of, not behind, actual sales shifts. Marketers have used tools like search trend data to track it as a cheap, fast proxy for brand health.
It measures something different from how often a brand is mentioned inside AI-generated answers, since it is entirely about what people type into a search box, not about what a model says once they ask it something. A brand can hold a strong, growing share of search while still rarely appearing in the answers AI systems generate for related category questions, because these are two separate systems measuring two separate behaviors.
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