What it is
A note in the page code saying "my main version lives at this address". It is needed when the same text opens at several addresses, so the search engine does not treat them as duplicates and split the ranking between them.
How we use it
We set it on every page. On the studio site the English version on the Russian domain points to the international site as the main address, so the same text does not compete with itself.
Where it helps a business
- One product opens from two catalogue sections at different addresses.
- Pages have addresses with ad tags (
?utm_source=...), and the search engine finds them as separate pages. - The same text lives on two domains, for example an English version.
How we use it
- On every page. Canonical points to the address without tags, so links from ads do not create duplicates.
- Between two sites. On the studio site the English version on the Russian domain names the international site as the main address, and language pairs are linked with hreflang.
Common problems
- Canonical to the home page from every page. A template bug after which the search engine drops everything but the home page.
- Canonical to a page closed from search. The search engine gets conflicting signals and decides on its own.
- None at all. The search engine picks the main address itself, not always well.
When you do not need it
If every page has exactly one address, there is nothing to think about. We still always set it: it is one line in the template that guards against future duplicates.