Canonical tag and noindex meta are two technical SEO tools for managing pages in Google search. They are often confused. Canonical says pages are duplicates and which is the main one. Noindex says don't index at all.
Canonical
Indicates the main version of a page. <link rel=\"canonical\" href=\"...\">. Google consolidates ranking signals.
Noindex
Tells Google not to add it to the index. <meta name=\"robots\" content=\"noindex\">. Googlebot reads but doesn't index.
Key difference
Canonical: duplicates are merged, the main is indexed. Noindex: the page isn't indexed at all and signals are lost.
When canonical
URL parameters (UTM, filter, session), multilingual versions, print, HTTPS migration.
When noindex
Admin pages, user profiles, internal search, login/register, low-quality content.
Don't combine
Canonical + noindex together is illogical and confuses Google.
Ranking signals
Canonical: signals merge. Noindex: signals are lost.
X-Robots-Tag
HTTP header noindex for PDFs, images, videos.
Canonical errors
Wrong URL, relative path, canonical loop.
Noindex errors
noindex, follow — don't index but follow links. noindex, nofollow — neither.
Sayt.uz
Self-canonical everywhere. /admin/, /cabinet/, /search? — noindex. Filter pages — canonical to the main category.