What a canonical URL is
A canonical URL is the preferred representative when identical or substantially similar content is available at more than one address. The canonical link element recommends that preferred URL, but search engines can choose another representative when signals conflict.
Self, other, and not declared
A self-referencing canonical supports the current URL. A canonical pointing elsewhere asks search engines to consolidate signals at another equivalent URL. Not declared means a reliable canonical was not found; it is a missing preference signal, not automatic proof that the page cannot be indexed.
Where WordPress duplicates come from
Common sources include HTTP and HTTPS, www and non-www hostnames, trailing-slash variations, tracking parameters, product variants, faceted shop URLs, attachment pages, and syndicated copies.
Canonical implementation checklist
- Choose one permanent HTTPS preferred URL.
- Output one canonical declaration.
- Point directly to a live, indexable destination.
- Align internal links and the XML sitemap with the preferred version.
- Use a permanent redirect when the duplicate should disappear.
- Do not use noindex as a substitute for duplicate consolidation.
Troubleshooting WordPress canonicals
Inspect the rendered source for rel="canonical", confirm there is one declaration, and verify the protocol, hostname, path, and trailing-slash format. Then review SEO plugin output, theme hooks, extensions, and cached HTML.
Continue with the WordPress indexability guide or install IndexToast to bring preflight into your publishing workflow.