Market share used to be measured in units sold, dollars spent, and shelf inches owned. That math assumed a buyer who walked the aisle, scrolled the listings, and compared options before deciding. The buyer is no longer doing that.
A growing share of buyers begin product research with AI engines — ChatGPT, Claude, Gemini, Perplexity, Google AI Overviews. The engines do the scrolling. The buyer gets one synthesized paragraph back, sometimes with two or three brand names inside, sometimes with one, sometimes with none.
Citation Share is the new measurement. It is the percentage of relevant prompts in a category where a brand is named, cited, or recommended by AI engines. Ask for the best CRM for small business one hundred ways across five engines: how many of those five hundred answers name Brand X? That number is Citation Share. It is comparable across categories, trackable over time, and — critically — improvable.
Market share follows Citation Share now. The brands that show up in the answer are the brands the buyer considers. The brands that don't show up have already lost the deal, and they don't know it, because there was never a click and never a session and never a referrer in the analytics. There was just absence. The work of AI Communications is to close that absence.
If you want the longer argument — what AI Communications is, why it matters now, and how it fits with public relations, GEO, and reputation — start with the manifesto.