Canonical tag
A canonical tag is a line of HTML, rel="canonical", that tells search engines which address is the main version of a page with copies.
A canonical tag is a line of HTML in a page's <head> that names the main address for that page. It looks like <link rel="canonical" href="https://fernhillcoffee.com/subscriptions">. When the same content can be reached at several addresses, the tag tells search engines which one to index and show.
For marketers, it's the quiet fix behind a lot of tidy reporting. Without it, one page can be split into several in search results, and the links and visits it earns get spread across them.
How to use it
Put the tag on every version of the page, including the main one, and point them all at the same address. A page that names itself as canonical is normal and helps.
A few rules keep it working. Use the full address, with https://. Point to a page that returns a normal 200 response, not a redirect or an error. Make sure the copies really are the same content. Don't point every page on a site at the home page.
For example, Fernhill Coffee's subscription page can be reached at /subscriptions, at /subscriptions?ref=newsletter and at /gifts/subscriptions. All three carry a canonical tag pointing to /subscriptions, so that's the address search engines show.
How strong is it?
The tag is a strong hint, not an instruction. Google weighs it with other signals, such as redirects and sitemaps, and can pick a different address if the pages don't match. Its guide to consolidating duplicate URLs explains each method. If an old address should never be shown again, a 301 redirect is the firmer choice.
Canonical tags and AI answers
AI answers cite pages by their address. When a page has several addresses and no canonical, its citations can be scattered across them, and the page looks less used than it is. A canonical on every copy gives search engines and AI platforms one address to find and cite.
In AnswerOrbit
Sources lists every page the answers used, by address. If the same page of yours appears twice under different addresses, add a canonical tag or a redirect. See Sources.