# What is an answer engine? ChatGPT, Gemini, Perplexity and more

> In short: An answer engine is a tool that replies to a question with a written answer, often naming brands and citing sources, instead of returning a list of links. ChatGPT, Gemini, Perplexity, Microsoft Copilot and Google's AI Overviews and AI Mode are the ones most people use.

Definition from Keats, published 2026-11-12, updated 2026-11-12. Canonical: https://getkeats.com/glossary/answer-engine

An answer engine takes a question and writes the answer. A search engine gives you ten links and lets you read; an answer engine reads for you, usually by running searches of its own, and tells you what it found, with the brands and sources it chose.

The ones that matter for most brands today:

- **ChatGPT**, which searches the web through OpenAI's search crawler when a question needs current information.
- **Gemini**, Google's assistant.
- **[Google AI Overviews](https://getkeats.com/glossary/ai-overviews)**, the written summary above Google's results, and **AI Mode**, Google's conversational search.
- **Perplexity**, which shows its sources beside every answer.
- **Microsoft Copilot**, built on Bing's index.

They differ in where they look, but they share the step that matters: before answering anything current, they search, read a few pages, and write from them. That's why the pages that rank for their searches, and the lists and threads they read when shopping a category, decide who gets named. Getting named in their answers is [AEO](https://getkeats.com/glossary/aeo). Keats asks the same questions on five of them every week: ChatGPT, Gemini, AI Overviews, AI Mode and Perplexity.


## Sources

- [Google Search Central: AI features and your website](https://developers.google.com/search/docs/appearance/ai-features), read 2026-11-12
- [OpenAI: Overview of OpenAI crawlers (OAI-SearchBot)](https://developers.openai.com/api/docs/bots), read 2026-11-12