# How Google Search works

> Google Search works in three stages: crawling, indexing and serving. Not every page makes it through each. Google does not guarantee any stage or accept payment to crawl or rank pages. AI Overviews and AI Mode draw on the same index.

- URL: https://geo.casa/foundations/how-google-search-works/
- Concept · Officially documented
- Reviewed: 2026-10-25

## The three stages

> **Officially documented:**
> "Google Search works in three stages, and not all pages make it through each stage":
>
> - **Crawling**: automated programs called crawlers download text, images and videos from pages Google found on the internet.
> - **Indexing**: Google analyses the text, images and video files on the page and stores the information in the Google index, a large database.
> - **Serving**: when a user searches, Google returns information that's relevant to the query.
>
> Sources: [Google Search Central: In-depth guide to how Google Search works](https://developers.google.com/search/docs/fundamentals/how-search-works)

Each stage has its own failure modes and its own controls:

| Stage | Can fail because | Controlled by |
|---|---|---|
| Crawling | Not discovered, blocked, server errors | Links, sitemaps ([XML sitemaps](https://geo.casa/crawling-indexing/xml-sitemaps/)), [robots.txt](https://geo.casa/crawling-indexing/robots-txt/) |
| Indexing | Low quality, duplicate, `noindex` | Content, [Canonical URL signals](https://geo.casa/crawling-indexing/canonical-signals/), robots meta rules |
| Serving | Less relevant than other pages | Relevance and quality for the query |

## What Google says it does not do

> **Officially documented:**
> Google does not accept payment to crawl a site more often or rank it higher. And "Google doesn't guarantee that it will crawl, index, or serve your page, even if your page follows the Google Search Essentials."
>
> Sources: [Google Search Central: In-depth guide to how Google Search works](https://developers.google.com/search/docs/fundamentals/how-search-works)

## Where AI features fit

> **Officially documented:**
> Google's generative AI features "are rooted in our core Search ranking and quality systems". They retrieve pages from the Search index to ground their answers.
>
> Sources: [Google Search Central: Optimizing your website for generative AI features on Google Search](https://developers.google.com/search/docs/fundamentals/ai-optimization-guide)

So the same three stages are the precondition for appearing in AI Overviews or AI Mode. See [Google AI Overviews](https://geo.casa/ai-search/google-ai-overviews/).

## Sources

- [Google Search Central: In-depth guide to how Google Search works](https://developers.google.com/search/docs/fundamentals/how-search-works)
- [Google Search Central: Optimizing your website for generative AI features on Google Search](https://developers.google.com/search/docs/fundamentals/ai-optimization-guide)