Canonical tag — rel="canonical"

A tag that tells search engines which version of a page is the main one when similar copies exist.

What it means

Sometimes the same content lives at more than one web address, for example when tracking codes are added to a link. A canonical tag is a short line of code in the head section of a page that says, in effect, "this is the main version, please treat it as the original". It is a link element with rel="canonical" that points to the preferred address.

How it works

When Google finds several near-identical pages, it groups them and picks one to show in search results. Your canonical tag is a strong hint about which one you prefer. It is not a command, though. Google also looks at other signals, such as internal links, redirects and your XML sitemap, and it may choose a different canonical if your signals disagree.

A simple example

A Surat saree shop sells a red Banarasi saree. Because it fits two categories, the page can be reached at both /wedding-sarees/red-banarasi and /silk-sarees/red-banarasi. Shoppers also arrive with UTM codes added from Instagram ads. The owner adds a canonical tag on every version pointing to /silk-sarees/red-banarasi. Google will most likely treat that address as the main page.

Why it matters

Without clear canonicals, search engines may waste time crawling duplicates, split ranking signals across several addresses, or show a messy version with tracking codes in results. A canonical tag keeps things tidy, so the right page appears in search and your reports are easier to read.

Beginner tips

Use a self-referencing canonical on every important page; most website builders and SEO plugins do this automatically.
Keep signals consistent: link internally to the canonical address and list only that version in your sitemap.
Check the page indexing report in Google Search Console to see which canonical Google actually chose.
Common mistake: pointing every page's canonical at the homepage, which tells Google your other pages are copies.