Fazley RabbiA canonical URL is the address you want search engines to treat as the main version of a page when the same or very similar content can be reached at more than one address. You state your preference with a canonical tag in the page's code, and Google usually follows it, together with other signals. Getting canonicals right keeps your ranking signals on one page instead of splitting them across copies, and stops Google showing an odd or unwanted version in search.
Why duplicate pages happen
Most duplicates aren't deliberate. They come from the way websites and platforms work:
- Tracking parameters. A link shared from a Facebook ad or a newsletter may carry
?utm_source=...or a click ID. The page is the same, but the address is different. See UTM links explained. - Protocol and www versions.
http://,https://, with and withoutwww, can all load the same page if the site doesn't redirect them to one. - Filters and sorting. A shop category sorted by price or filtered by colour can create many addresses with nearly identical content.
- Product variants. A shirt in five colours might have five pages with the same description.
- Printer-friendly versions, and tag or archive pages on blogs that repeat the same posts.
- Copied text. Product descriptions supplied by a manufacturer and used by many shops, or the same page published on two of your own domains.
Google doesn't punish ordinary duplicates like these. It groups them and picks one to show. The trouble is that it may pick the one you'd rather it didn't, and your links and signals get split between copies.
What the canonical tag does
The canonical tag is a single line in the <head> section of a page:
<link rel="canonical" href="https://yourdomain.com/products/jute-tote-bag">
It says: "of all the versions of this content, this address is the main one." Put it on the duplicates, pointing to the main version, and put a self-referencing canonical on the main version itself. Many platforms and SEO plugins add self-referencing canonicals automatically, but it is worth checking that they point where you expect.
Google treats the canonical as a strong hint, not a command. If your other signals disagree, such as internal links pointing to a different version, or a sitemap listing the duplicate, Google may choose differently.
Canonical, redirect or noindex?
These three tools are often confused. They do different jobs.
| Tool | What it does | Use it when |
|---|---|---|
| Canonical tag | Keeps both pages available but names the main one | Visitors need the variant (a sorted list, a tracked link), but search should show the main version |
| 301 redirect | Sends visitors and search engines from the old address to the new one | The old page shouldn't exist any more, such as after a URL change or when merging two pages |
| noindex | Asks search engines not to show the page at all | The page is useful to visitors but has no place in search, such as a thank-you page |
A common error is using a canonical where a redirect belongs. If a page has moved for good, redirect it. Canonical tags are for pages that still need to exist.
Special cases worth knowing
Bangla and English versions
Translated pages are not duplicates. Your Bangla page and its English version should each have a canonical pointing to itself, and be connected with hreflang tags so Google shows each reader the right language. Pointing the Bangla page's canonical at the English one can drop the Bangla page from search. See hreflang for a Bangla and English site.
Paginated lists
Page two of a product category isn't a copy of page one; it lists different products. Each page in a series usually keeps its own self-referencing canonical rather than all pointing to the first page.
Similar product pages
If variants really are the same product, one page with a colour or size selector is often cleaner than separate pages. If they need separate pages, write something specific on each. More in product and category pages that rank.
How to check your canonicals
- Open a key page, view the page source, and search for
canonical. Is there one, and does it point to the right address? - Type the
http,https,wwwand non-wwwversions of your address. They should all end up at one version. - In Google Search Console, run URL Inspection on important pages. It shows the canonical you declared and the one Google selected. If they differ, look for conflicting signals.
- Make sure your sitemap lists only canonical URLs; see XML sitemaps and robots.txt explained.
In short
Choose one address for each piece of content, point every copy at it, redirect pages that have moved, and keep your internal links and sitemap consistent with that choice. If your site has grown messy over time, my SEO, AEO and GEO service can help untangle it.