What Is a Canonical Link and How Does It Affect Your Website?
If you've spent any time digging into SEO or web development, you've probably encountered the term canonical link — and possibly moved past it quickly because it sounded technical and optional. It's neither. Understanding what a canonical link actually does can prevent one of the most quietly damaging SEO problems a website can have: duplicate content.
The Core Concept: What a Canonical Link Actually Is
A canonical link (also called a canonical tag or rel="canonical") is a small piece of HTML that tells search engines which version of a page is the "official" one. It lives in the <head> section of a web page and looks like this: