An HTML attribute (rel="nofollow") that tells search engines not to pass link equity through a link, originally created to fight comment spam.
The `rel="nofollow"` attribute is added to anchor tags to signal that the linking site does not vouch for the destination. Google introduced it in 2005 as a way to combat comment spam: blog owners could let users post links without unintentionally passing their own authority to spam sites.
In 2019, Google expanded the system with two additional values: `rel="ugc"` (user-generated content) and `rel="sponsored"` (paid or sponsored links). Google also changed nofollow from a strict directive to a hint, one of several signals Google may consider, though in practice most nofollow links still pass no authority.
Nofollow is how you disclose untrusted or commercial links to search engines without being penalized for linking to them. Paid links and affiliate links should use `rel="sponsored"`. User-submitted links (comments, forum posts, profile fields) should use `rel="ugc"`. General untrusted outbound links can use `rel="nofollow"`.
Failing to mark paid links appropriately is one of the clearest violations of Google's link policies and can result in manual actions against both the linking and receiving site. Conversely, nofollowing all outbound links (a once-common "PageRank sculpting" tactic) is a waste of effort. Modern Google largely ignores it, and legitimate outbound links to authoritative sources are a positive quality signal.
The three link relationship values can be combined and applied to any anchor tag:
<!-- A normal editorial link, passes link equity --> <a href="https://ahrefs.com/blog/seo-stats/"> Ahrefs SEO statistics </a> <!-- An affiliate link, paid commercial relationship --> <a href="https://example.com/product?ref=abc" rel="sponsored nofollow"> Our recommended tool </a> <!-- A user-submitted comment link --> <a href="https://random-user-site.com" rel="ugc nofollow"> Commenter's website </a> <!-- A link to a source you do not want to vouch for --> <a href="https://example.com/disputed-claim" rel="nofollow"> According to this source </a>
The combined `rel="sponsored nofollow"` and `rel="ugc nofollow"` patterns are a safe default. They give the precise signal Google prefers while also working for older systems that only recognize nofollow.
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