# URL parameters

Category: [Technical SEO](https://seo-geo-glossary.com/en/glossary/category/technical-seo/) › [URLs & domains](https://seo-geo-glossary.com/en/glossary/category/technical-seo/urls-domains/) · Also known as: query parameters, query string parameters

**URL parameters** are key and value pairs added to a URL after a question mark. They pass extra information to the server or the page, for example a sort order, a filter or a campaign tag. The part of the URL that holds them is the query string.

## How are URL parameters written?

Google's documentation recommends an equals sign (`=`) between key and value and an ampersand (`&`) between multiple parameters:

```txt
https://example.com/category?category=dresses&sort=low-to-high
```

Special characters are percent-encoded, so a space becomes `%20` (MDN).

## Which jobs do URL parameters do?

Typical uses are filtering and sorting in shops, site search, pagination, language selection and campaign tracking such as UTM tags (Botify). Some change the content of the page, others do not.

## What do URL parameters mean for SEO?

Each parameter combination is a new URL. Google notes that crawlers cannot tell whether faceted navigation URLs are useful without crawling them first, so they often access a very large number of such URLs before concluding they are not. That slows the discovery of new content.

If parameter URLs should not appear in search, Google lists these options: block the parameters in robots.txt, use fragments instead of parameters for filters, point filtered pages to the unfiltered version with `rel="canonical"`, or mark links with `rel="nofollow"`. If they should be indexed, use standard `&` separators, keep the order of filters consistent and return a 404 when a combination has no results.

## Common mistakes

- **Filters that can be combined without limit.** Google notes that crawlers often access a very large number of faceted navigation URLs before concluding they are not useful, which slows the discovery of new content.
- **Missing 404 for empty combinations.** For parameter URLs that should be indexed, Google advises returning a 404 when a filter combination has no results.
- **Relying on the URL Parameters tool.** Google deprecated the Search Console tool in 2022 and says its crawlers learn how to handle parameters on their own. robots.txt rules remain for more control.

*Diagram: Anatomy of a URL.* A URL broken into its parts. RFC 3986 defines scheme, host, path, query and fragment. Only the browser evaluates the fragment after #, it is not sent to the server.

*Diagram: Duplicate cluster and canonical URL.* Google groups identical or very similar pages into a cluster and picks one canonical URL. According to Google, redirects and rel="canonical" are strong signals and the sitemap is a weak one. Your own preference remains a hint.

*Diagram: How filters multiply URLs.* Own calculation example. Three filters are enough to turn one category into thousands of URLs. Google describes two approaches, depending on whether the filtered pages are meant for search.

## Related terms

- [Query string](https://seo-geo-glossary.com/en/glossary/query-string/index.md)
- [UTM parameters](https://seo-geo-glossary.com/en/glossary/utm-parameters/index.md)
- [Faceted navigation](https://seo-geo-glossary.com/en/glossary/faceted-navigation/index.md)
- [Sort parameters](https://seo-geo-glossary.com/en/glossary/sort-parameters/index.md)
- [URL](https://seo-geo-glossary.com/en/glossary/url/index.md)
- [Canonical tag](https://seo-geo-glossary.com/en/glossary/canonical-tag/index.md)

## Sources

- [URL structure best practices for Google Search – Google Search Central](https://developers.google.com/search/docs/crawling-indexing/url-structure)
- [Managing crawling of faceted navigation URLs – Google Search Central](https://developers.google.com/search/docs/crawling-indexing/crawling-managing-faceted-navigation)
- [URL: search property – MDN Web Docs](https://developer.mozilla.org/en-US/docs/Web/API/URL/search)
- [What are URL parameters? – Botify (secondary)](https://www.botify.com/insight/what-are-url-parameters)
- [Spring cleaning: the URL Parameters tool – Google Search Central Blog](https://developers.google.com/search/blog/2022/03/url-parameters-tool-deprecated)

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Last updated: October 8, 2026
URL: https://seo-geo-glossary.com/en/glossary/url-parameters/