AI visibility is the degree to which your business appears as a cited or mentioned source in answers produced by AI language models — specifically ChatGPT, Claude, Perplexity, and Gemini — when users ask questions relevant to your product, service, or expertise. It is the AI-age equivalent of Google page-one ranking, with one critical difference: AI models typically cite three to five sources per answer rather than displaying ten blue links. The businesses cited in those answers get the inquiry. The businesses not cited are functionally invisible to an increasingly large share of buyer research behavior.