This translation has not been editorially reviewed yet. The German version is authoritative. Deutsche Fassung
Indexing
What is a canonical address, and what is it for?
The canonical address is a note in a page's source code that tells search engines which of several reachable variants is the authoritative one. The same page is often reachable under multiple addresses — with and without www, or with tracking parameters attached from ad campaigns. Without the note, visibility spreads across these duplicates. The "Indexing" audit area checks whether the note is present.
One page, many addresses
To you, your homepage is one page. Technically, it's often reachable under several addresses: with www and without, with a trailing slash and without, with tracking parameters attached from newsletters or ads. To a search engine, each of these forms is initially a separate address — and therefore potentially a separate page with identical content. This is called duplicate content: the same content under multiple addresses. The consequence isn't a penalty, but dilution — links and signals spread across several versions instead of benefiting a single one.
The note in the source code
The solution is a single note in the technical part of every page: the canonical element. It names the one address that should count — comparable to a company's official letterhead, reachable under several phone numbers but stating one main number. Search engines then bundle every variant under this main address. Our check looks in the source code for whether the note is present. If it's missing, this rule gets 0 out of 10 points, and the finding reads: duplicate content risk. The note itself is quick to set up with any common website system.
Bundled visibility instead of scattered duplicates
The benefit shows especially after ad campaigns. Ads and newsletters attach tracking parameters to every address, so success can be measured — this creates many variants of the same page. With a canonical note, all these visits and links flow to the one main address. Without it, the variants compete against each other for the same spot in search results. The note costs nothing, is generated automatically by common website systems, and only needs setting up correctly once. That's why it belongs on every page — as a self-reference, it does no harm even where no variants exist yet.
- Open the source code of an important page and search for "canonical" — the note should be present on every page.
- Decide on a main form of your domain (with or without www) and use it consistently across all materials.
- Ask your agency to output the canonical note automatically on every page — common systems can do this out of the box.
- Check after ad campaigns whether addresses with attached parameters point to the base address.
