AI SEO Glossary

An AI Search Engine is broadly any search system that uses artificial intelligence, specifically large language models, to understand queries and generate responses. The term encompasses a spectrum of products: from Google, which layers AI on top of traditional search infrastructure, to purpose-built answer engines like Perplexity, which use AI as the primary interface. AI search engines share a common characteristic in that they move the user experience from link discovery toward answer delivery, reducing the browse-and-click behavior that defined search for the previous two decades.

As of 2026, the most widely used AI search engines are Google AI Overviews and Google AI Mode, which reach the broadest audience by volume through Google’s existing user base; ChatGPT Search, which is used by ChatGPT’s hundreds of millions of monthly active users; Perplexity AI, which has built a loyal base among researchers, professionals, and technical users; Microsoft Copilot Search, embedded across the Microsoft 365 ecosystem; and Grok on X. Beyond these, Claude.ai, You.com, and various regional AI search tools make up a growing tail of the market.

Why it matters: Brands that focus only on Google are already missing meaningful AI search volume. Tracking visibility across the top five platforms gives a far more accurate picture of where your audience is finding information about you.