SEO glossary

Canonical tag

An HTML link element (rel=”canonical”) that tells search engines which URL is the preferred version of a page with duplicate or very similar content.

Canonical tags consolidate ranking signals from duplicates, such as URLs with tracking parameters or printer versions, into one main URL. Google treats the canonical as a strong hint, not a directive.

Every indexable page should have a self-referencing canonical tag pointing to its own clean URL.

Related tools

XML Sitemap ValidatorFind and validate the XML sitemap of any website: XML errors, URL count, sitemap indexes, lastmod dates, duplicates and robots.txt declaration.HTTP Header CheckerSee all the HTTP response headers of any URL, with checks for indexing (X-Robots-Tag), compression, caching and security headers.Redirect CheckerFollow every redirect of a URL: see each hop, its status code (301, 302, 307, 308), redirect chains, loops and the final destination.

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