What is a canonical tag?
A canonical tag (also known as rel="canonical") is an HTML element that tells search engines which version of a URL is the "master" copy of a page. It is placed in the <head> section of your HTML document.
Duplicate content is one of the most common SEO problems. The same page can often be accessed through multiple URLs — with or without www, with trailing slashes, with query parameters, or across HTTP and HTTPS. When search engines find the same content at different URLs, they have to guess which version to index and rank, which can dilute your page authority.
By adding a canonical tag, you explicitly tell Google and other search engines: "This is the preferred URL for this content. Please consolidate all ranking signals here." This prevents your pages from competing against themselves in search results and ensures that link equity flows to the correct URL.
Best practice is to include a self-referencing canonical tag on every page of your site, even when there are no duplicate versions. This acts as a safeguard against future duplication issues and gives search engines a clear, consistent signal about your preferred URLs.
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