Nofollow is a link attribute that tells search engines not to follow a particular link, or to follow it only to a limited degree. It is added in the HTML and shows Google that little or no trust should be passed to the linked page.
The attribute usually looks like this: rel=”nofollow”.
When is nofollow used?
Nofollow is common on paid links, advertising, comments and external links where you do not want to take responsibility for the destination.
Typical uses:
- sponsored posts
- affiliate links
- blog comments
- forum posts
- external links to unfamiliar sites
Nofollow once meant Google ignored the link entirely. Today Google treats it more as a hint and decides for itself how much weight to give it.
Why nofollow matters
It helps avoid unnatural link building and spam. On paid or untrusted links in particular, the attribute keeps you from passing SEO signals to other sites.
For SEO it matters because not every link should automatically pass authority or trust.