nofollow

Nofollow is an HTML rel attribute value used on hyperlinks to indicate that search engines should not pass ranking credit or follow the linked URL. It was introduced in 2005 by Google as a way to combat spam in user-generated content and to avoid endorsing untrusted links.

Historically, nofollow was interpreted as a directive that prevented search engines from passing PageRank and from discovering the linked page through that link. In March 2020 Google announced that nofollow would be treated as a hint rather than a strict directive for crawling and indexing, and it introduced two additional values, sponsored for paid links and ugc for user-generated content, to clarify link intent. Other search engines may interpret values differently, but the general move has been toward signals rather than commands.

In practice, rel values are space-separated and can be combined, for example rel="nofollow sponsored" or rel="ugc nofollow." The attribute can also be used with security-related values such as noopener and noreferrer, which affect browser behavior rather than ranking. The nofollow value remains widely supported for backward compatibility, but sites are encouraged to use the newer values (sponsored, ugc) when appropriate to improve clarity about link intent.

Usage guidelines include applying nofollow to links in untrusted user-generated content, marking paid links with sponsored, and clearly labeling links in sponsorship or advertisement contexts. While nofollow and related values influence how search engines treat a link, adoption and interpretation can vary between engines, so it should not be relied on as a guarantee of exclusion from crawling or indexing in all cases.