A canonical URL is a web page address that you designate as the primary version of a page when there are multiple pages with identical or similar content on your website. By using a canonical URL you tell search engines which page they should prioritize and index, which helps avoid problems with duplicate content (duplicate content). This is important for SEO, as it ensures search engines focus on one version of your content and thus avoid splitting the ranking between multiple pages.
How does a canonical URL work?
When a website has multiple pages that show the same or very similar content, search engines can get confused about which version they should index and rank in the search results. A canonical URL solves this by specifying one "official" version. This is done by adding the following code in the HTML header on the pages you want to mark as non-canonical:
<link rel="canonical" href="https://www.eksempel.dk/kanonisk-side">Here you tell search engines that https://www.eksempel.dk/kanonisk-side is the preferred URL, even though similar versions of this page also exist.
When should you use a canonical URL?
Canonical URLs are used in situations where multiple pages have the same content or very similar content. This can, for example, happen when:
- There are multiple versions of a page: Such as a mobile version, printer-friendly version, or URLs with different parameters (e.g., filtered product pages).
- Content is accessible via multiple URLs: For example, when both http:// and https:// versions of a page exist.
- Duplicate content: When similar content is shown on different pages or subcategories, e.g., product descriptions in an online shop.
Why are canonical URLs important?
Canonical URLs are essential to avoid SEO problems with duplicate content. If several pages with the same content compete for ranking, it can result in lower positions for all pages, because search engines don't know which page to prioritize. By specifying a canonical URL you help with:
- Avoid SEO-splitting: Ensures that one page receives all SEO value and backlinks instead of being spread across several duplicates.
- Improve ranking: Search engines can focus on the primary page and increase the chances of a better position in the search results.
- Organize your content better: Ensures that users and search engines can easily find the right version of your content.
A correctly set up canonical URL is important for optimizing the website's visibility and avoiding the negative consequences of duplicate content.