# Search algorithm

Category: [Basics & Search Engines](https://seo-geo-glossary.com/en/glossary/category/basics-search-engines/) › [Search engines & search](https://seo-geo-glossary.com/en/glossary/category/basics-search-engines/search-engines-search/)

A **search algorithm** is the set of rules a search engine uses to select pages for a query and put them in order. In SEO the term usually means Google's algorithm. Google rarely uses it and speaks of ranking systems. In computer science the word covers general search methods such as binary search, which have little in common with web search.

## How does Google describe its algorithm?

Google says it uses automated ranking systems that look at many factors and signals about hundreds of billions of web pages and other content in its index to present the most relevant, useful results, all in a fraction of a second. There is no single algorithm. Several systems work together. Google lists these as active, among others:

- **Link analysis systems and PageRank**
- **BERT, RankBrain, MUM and neural matching**, which help interpret language and concepts
- **Spam detection systems**
- **Deduplication systems**, **freshness systems** and **passage ranking**

Four systems appear as retired. Google notes they are listed for historical purposes and have been incorporated into successor systems or made part of the core ranking systems. They are Hummingbird, Panda, Penguin and the helpful content system.

Google also says relevance is determined by hundreds of factors, such as location, language and device. It does not publish a full list.

## What does this mean for SEO?

No complete public description of the algorithm exists. SEO works from Google's published guidance, observations and tests. Google says it regularly improves its ranking systems and shares updates when they are useful to creators and others.

## Example

For a query like "laptop review", Google first finds matching pages in the index. The ranking systems then weigh them for relevance, quality and context such as location, so the order can differ between people.

## FAQ

**Is there one Google algorithm?**
No. Google's documentation lists many ranking systems.

**Do Panda and Penguin still exist?**
Google lists them as retired systems that were folded into other systems.

## Related terms

- [Search engine](https://seo-geo-glossary.com/en/glossary/search-engine/index.md)
- [SEO (search engine optimization)](https://seo-geo-glossary.com/en/glossary/seo/index.md)
- [SEM (search engine marketing)](https://seo-geo-glossary.com/en/glossary/sem/index.md)

## Sources

- [Guide to Google Search ranking systems – Google Search Central (updated 2025-12-10)](https://developers.google.com/search/docs/appearance/ranking-systems-guide)
- [How Google Search works – Google Search Central (updated 2025-12-18)](https://developers.google.com/search/docs/fundamentals/how-search-works)
- [Google Search Central Blog](https://developers.google.com/search/blog)

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Last updated: October 7, 2026
URL: https://seo-geo-glossary.com/en/glossary/search-algorithm/