# Canonical URL

> A canonical URL is a tag that tells search engines which address is the main one when the same content can be reached from several addresses. It is written in the page code as rel="canonical". Duplicate addresses then stop splitting each other's strength.

- URL: https://radkod.com/en/glossary/canonical-url
- Publisher: RadKod
- Published: 2026-07-30

## What is a canonical URL?

A canonical URL is the main address of a piece of content. It is set in the page code with a rel="canonical" tag. When the same content appears at several addresses, it tells search engines which one is the real one.

Here is an everyday case. A product in your online store opens at both /shoes/white-trainers and /sale/white-trainers. Visitors from ads also arrive with extras such as ?utm_source=... on the end. To a person these are all one page. To a search engine they are separate addresses. The canonical tag makes them all point to the first address, and that address shows in search results.

## Why does it matter?

Duplicate addresses make it harder for a search engine to decide which page to show, and the value of incoming links can get split between them. The canonical tag pulls that together. It works as a hint, and a search engine may decide differently if other signals disagree. That is why internal links, the sitemap and the canonical tag should all point to the same address. If a page has moved for good, use a [301 redirect](/en/glossary/301-redirect) instead.

The canonical tag is one of the technical parts of [SEO](/en/glossary/seo). We explain how to keep addresses intact in [redesign without losing SEO](/en/blog/redesign-without-losing-seo). On the sites we build, every page writes its canonical address automatically, as described on our [web design](/en/services/web-design) page.

## Frequently asked questions

### What is the difference between a canonical tag and a 301 redirect?

A 301 redirect sends visitors from the old address to the new one, and the old one no longer opens. With a canonical tag both addresses open, but search engines are told which one is the main one.

### Should every page have a canonical tag?

Yes, it is a good habit. A page with no duplicates points to itself. That way, addresses with added parameters later cause no trouble.

### How can I see which canonical Google chose?

The URL Inspection tool in Google Search Console shows which address Google picked as canonical.

## Sources

- [How to specify a canonical URL with rel="canonical" and other methods](https://developers.google.com/search/docs/crawling-indexing/consolidate-duplicate-urls), Google Search Central