A canonical link tag is an HTML element used in SEO to tell search engines which version of a webpage is the preferred or original one when there are multiple pages with similar or duplicate content. It helps prevent duplicate content issues by specifying the 'canonical' URL that should be indexed and ranked.
Synonyms: canonical tag, canonical URL tag, rel canonical, canonical link element

Duplicate content can confuse search engines, leading to lower rankings or split ranking signals. The canonical link tag consolidates these signals by pointing to a single preferred URL, improving SEO performance.
Place the canonical link tag in the section of your HTML. It looks like this: . This tells search engines that the URL in the href attribute is the main version.
If you have a product page accessible via multiple URLs due to tracking parameters or sorting options, use the canonical tag to point all variations to the main product page URL. This avoids duplicate content penalties and consolidates ranking.
What happens if I don’t use a canonical link tag? Search engines might index multiple versions of the same content, which can dilute your SEO rankings.
Can the canonical tag be used across different domains? Yes, but it should be used carefully to avoid confusing search engines.
Is the canonical link tag a ranking factor? It doesn’t directly boost rankings but helps search engines understand your site structure better, which can improve SEO.