# Canonical URL

> What a canonical declares, why it is a hint rather than a directive, and the mistakes that quietly de-index pages.

Source: https://netweft.com/glossary/canonical-url
Updated: 2026-03-05

**The URL a site declares to be the preferred address for a piece of content, using a rel=canonical link. It consolidates duplicate or near-duplicate URLs so that ranking signals accrue to one address instead of being split.**

A canonical says: of the several URLs that serve this content, this is the one
that counts. Tracking parameters, print views, session IDs, HTTP and HTTPS,
with and without a trailing slash — all of them can serve the same page, and
without a canonical the signals split across them.

**It is a hint.** Search engines usually honour a canonical and sometimes
overrule it, typically when the declared canonical is clearly not equivalent to
the page declaring it.

**Self-referencing canonicals are correct.** A page that is its own canonical
should say so. It costs nothing and removes ambiguity.

**The failure mode is severe.** A canonical pointing at the wrong page — a
template-wide canonical to the homepage is the classic — tells the engine every
page on the site is the homepage. Pages disappear from results without any
obvious error. This is exactly the class of finding a [site
audit](/features/site-audit) exists to catch, and it is why netweft classifies it
as high severity rather than as one line among four hundred.