nofollow
nofollow is a link attribute, rel="nofollow", that asks search engines not to count a link as an endorsement of the page it points to.
nofollow is a value you add to a link, rel="nofollow", to tell search engines you don't vouch for the page it points to. It's how sites link to things without passing on their ranking credit: comments, forum posts, ads and pages they aren't sure about.
For a marketer, it mostly comes up in two places: marking your own paid or untrusted links, and working out what a link to you is worth.
How it works
You add the attribute to the link's HTML:
<a href="https://example.com" rel="nofollow">Example</a>Google has two more specific values. sponsored is for links that are paid for or given in return for something. ugc is for links in content your users wrote, like comments and forum posts. nofollow covers everything else you don't want to endorse. Google treats all three as hints, and explains them in its guide to qualifying outbound links.
Many sites add nofollow to every outbound link by default. Large publishers, social networks and wikis often do.
Is a nofollow link worth having?
For rankings, it counts for less than a followed link. For everything else, it can be worth just as much. People still click it, and the page around it still says what it says about you.
For example, say a busy forum thread asks "which coffee subscription should I try?" and the top reply recommends Fernhill Coffee with a nofollow link. The link may pass little ranking credit. But if an AI platform reads that thread, the reply naming Fernhill is what it can repeat, and the link has no say in that.
nofollow and AI platforms
nofollow is a ranking signal for search engines. It isn't a way to keep a page out of AI answers, and it doesn't stop a bot from reading the page it points to. If you want to keep a bot out, use robots.txt, and check each AI company's own page about its bots.