A canonical tag is a HTML element that tells search engines which web pages with similar or even the same content should be indexed.
A canonical tag is used primarily when the same content is on two web pages. The canonical link or URL indicates which of the web pages the search engine can consider and which it can neglect. In other words, it indicates which of the web pages is the original resource. It is also important to avoid „Duplicate Content“. This often leads to penalties on the part of Google.
What is Duplicate Content?
Duplicate content is defined as “substantial blocks of content within domains or across domains that either completely match other content or are significantly similar.” In other words, duplicate content exists when two or more pieces of content are so similar that they could be considered the same.
Google penalizes websites for duplicate content because it affects the user experience. When users submit a search query, they expect to see unique content in response to the search, as well as different perspectives on the desired topic. If there are too many results with similar or identical content, it becomes difficult for users to find the information they are looking for. To avoid this, Google penalizes sites that publish duplicate content to keep search results relevant and useful to users.
This is where a canonical tag comes into play, which is meant to avoid indexing both content and thus prevent duplicate content from occurring.
Thematically relevant sub-pages:
