What is an AI search engine? Which ones exist and which Americans use (2026)

An AI search engine answers your question with a written answer, instead of a list of ten links. The system searches the web itself, reads the pages and summarizes them, usually with the sources listed. In the US it comes down to six platforms: ChatGPT, Google (with AI Overviews and AI Mode), Gemini, Microsoft Copilot, Claude and Perplexity. ChatGPT is by far the biggest.

How is it different from a regular search engine?

A regular search engine shows where the answer is. An AI search engine gives the answer itself. In Google, you choose which of the ten links to open. In an AI search engine, the model already made that choice. Often it names only two or three providers.

Take someone who asks: “Which physical therapist in Denver helps with back pain?” Google shows a list of practices, a map and reviews. An AI search engine names a few by name and explains why. If your practice is not in that answer, you do not exist for that question.

That changes what “being found” means. In position 6 in Google you still get a share of the clicks. In an AI answer you are mentioned, or you are not. So what matters is whether your page is the source the answer comes from. That field is called GEO, Generative Engine Optimization. How search keeps changing is in the future of search.

Which AI search engines do Americans use?

ChatGPT, by a wide margin. That shows in Statcounter’s numbers. Statcounter counts page views on a large network of websites that use its tracker. When someone clicks a source link in an AI chatbot and lands on one of those sites, Statcounter counts that as a referral from that chatbot. For the US, the split in August 2026 looked like this:

AI search engine	Share of referrals from AI chatbots, US, August 2026
ChatGPT	72.12%
Google Gemini	11.68%
Microsoft Copilot	7.95%
Claude	4.44%
Perplexity	3.74%

Read these numbers with two caveats. First, Statcounter measures click-throughs, not how many people use a chatbot. People also click through less often from a chatbot than from regular search. Second, Google’s own AI answers are not counted here: AI Overviews and AI Mode live inside Google Search. And the shares move from month to month, so treat them as a direction, not a fixed ranking.

Which AI search engine should you use yourself?

If you want to check where an answer comes from, choose ChatGPT with search or Perplexity. Both put their sources next to the answer. Gemini does not do that for every answer. All of them have a free version.

	Free to use	Sources visible	Where available
ChatGPT	Yes, search even works without an account	Yes, when ChatGPT searches the web	Browser (chatgpt.com), desktop and mobile apps
Google AI Overviews and AI Mode	Yes, part of Google Search	Yes, with links to the sources	Built into Google Search and the Google app
Gemini	Yes, with a Google account	Sometimes, not with every answer	Browser, Android and iPhone apps
Microsoft Copilot	Limited free version, plus paid plans	Yes	Browser, Windows, Edge, Android and iOS apps
Perplexity	Yes, plus a paid Pro version	Yes, with every answer	Browser, iOS and Android apps
Claude	Yes, with limits, plus paid plans	Yes, when it searches the web	Browser, desktop and mobile apps

We checked these against the platforms’ own help pages in October 2026, for example ChatGPT search, Google AI Overviews, Google AI Mode and Perplexity. Features change often, so check before you rely on a detail.

If you already search in Google, you do not need to install anything. AI Overviews appear by themselves for questions where Google thinks a summary is useful.

The AI search engines one by one

ChatGPT

About seven in ten referrals from AI chatbots in the US come from ChatGPT. With search turned on, ChatGPT consults the live web and names the pages its answer comes from. People ask it for advice, compare providers and choose products. If you are missing here, you are missing the platform with by far the most referrals. The approach is in getting found in ChatGPT.

Google: AI Overviews and AI Mode

AI Mode is a separate tab in Google’s search results where you have a conversation. Google splits your question into sub-questions and searches all of them. That means a page outside the top 10 can also become the source. AI Overviews sit above the regular results and appear only when Google thinks a summary adds something. What that means for your site is in getting found in Google AI Overviews.

Gemini

Gemini is Google’s standalone AI assistant, in the browser and as an app. It uses Google’s search results as its foundation, so solid classic SEO counts for more here than on other platforms. Not every answer has sources. More in getting found in Gemini.

Microsoft Copilot

Copilot is built into Windows and the Edge browser, and is available as an app for Android and iOS. Anyone working on Windows already has it at hand. Copilot leans on the Bing index. For B2B businesses that is a reason to set up Bing Webmaster Tools, Bing’s version of Search Console. See getting found in Microsoft Copilot.

Claude

Claude from Anthropic had about 4 percent of US referrals in August 2026, and its usage is growing. It can search the web and cites its sources when it does. More in getting found in Claude.

Perplexity

Perplexity is made for people who want well-supported answers with visible sources. Every answer has clickable sources, so you see right away whether your site is among them. Its share of referrals is small, but it pays off if your customers compare carefully before they buy. How to stand out there is in getting found in Perplexity.

The rest

There are also models such as Grok, DeepSeek and Mistral. For most small businesses they matter less than ChatGPT and Google.

How does an AI search engine choose its sources?

Every AI search engine works in three steps. First the system turns your question into search queries. Then it fetches pages. Then it writes an answer from what it reads there. You can drop out at each point:

1. Fetching: the crawler, the program that fetches pages, must be able to read your page. Most AI crawlers do not run JavaScript, so text that only appears through a script is invisible to them. See how AI crawlers read your site.
2. Choosing: the system picks pages that answer the question directly and factually, preferably in the first paragraphs.
3. Confirming: is your business also mentioned on other sites, in reviews, comparisons and trade media? Then you are more likely to get into the answer than a business that only writes about itself.

The differences per platform are worked out in how ChatGPT, Perplexity and Gemini choose their sources.

How does your business get into those answers?

Start with ChatGPT and Google. ChatGPT is by far the largest chatbot, and through Google you reach everyone who searches the regular way. Gemini often follows by itself if you do Google well. Copilot deserves attention if you have business customers. Perplexity counts if your customers compare carefully before they buy.

So a physical therapy practice in Denver does not need six strategies. The page about back pain answers “what does physical therapy for back pain cost?” at the top. That text is plain HTML, so every crawler reads it. And the practice asks patients for reviews that mention Denver and the condition. That works for all of them.

How to approach it step by step, with the pitfalls per platform, is in our guide to getting found in AI search engines. Want a fixed plan with a baseline? Follow GEO optimization in six steps.

Measuring which AI search engine mentions you

Search Console shows how often you appear in Google. Whether ChatGPT mentions you, you cannot see there. You measure that separately, and more than once, because AI answers shift from day to day.

GreatCompany asks your customers’ questions in ChatGPT, Gemini and Perplexity every day. You see for which questions you are mentioned, and for which your competitor is. You also see your positions in Google. For the practice in Denver it could look like this: for the back pain question, Perplexity mentions the practice, while ChatGPT names only two competitors for that question. Then you know where to start. How the measurement works is on the prompt tracker page.