Duplicate content: definition, relevance for SEO and solution

Why is it important for SEO to exclude duplicate content?

Duplicate content causes three major problems for search engines:

• The services do not know which version(s) should be indexed and which should not.
• It is difficult for them to assess whether they should direct the link metrics (trust, anchor text, authority, link juice, etc.) to a single page or whether they need to distribute them across multiple versions.
• It is not known which version(s) should rank for the search results.

For website owners, this means an increased risk of massive ranking and traffic losses. These losses are often due to two main problems:

• For an optimal search result, search engines very rarely display multiple versions of the same content and are therefore forced to select the variant that is most likely to deliver the best result in the case of duplicate content. This can dilute the visibility of the duplicates.
• The link value is also weakened, as other websites have to choose between the duplicates. Instead of all links pointing to one content, they link to several parts, which spreads the link value across the duplicates. Incoming links are a strong ranking factor. This distribution can therefore have a significant impact on the visibility of content or relevant pages in searches.

The end result: pages and their content do not achieve the visibility in search engines that they would without duplicates.

How can you fix problems with duplicate content?

First of all, you should of course make sure that you do not publish any duplicate content at all. However, this is not always possible or practicable. For example, it makes sense to make the homepage accessible via http and https URLs and, particularly in the case of large e-commerce sites, it is hardly possible to provide unique text for all similar products that may only differ in one respect.

In these and similar contexts, you have various options for limiting the negative effect of duplicate content on search engines. The easiest and most effective way is often to use the so-called canonical tag (<link rel="canonical" href="example URL/>)". By inserting the tag into a page, you can (in simple terms) clearly tell the search engines which content is the main content and should be used for the ranking.