relnofollow

Rel=nofollow is an HTML attribute value applied to hyperlinks. When a link includes rel="nofollow," it signals to search engines that the linking page does not endorse the target and that PageRank or other ranking signals should not be passed through that link. It is an instruction, not a strict prohibition; search engines may still crawl or index the linked page for purposes of discovery or other signals.

Origin and purpose: Introduced by Google in 2005 to combat spam and link manipulation on blogs and forums, nofollow became a standard for marking unsolicited or paid links as non-endorsing. Other search engines adopted similar concepts over time, though implementations have varied.

Current practice and evolution: In 2019–2020, Google reframed nofollow as a hint for crawling and indexing rather than a hard directive. The company introduced two new link values, rel="sponsored" for paid or promotional content and rel="ugc" for user-generated content, and recommended using them in appropriate contexts. Nofollow remains recognized for backward compatibility, but many webmasters now use the new values to more precisely categorize links. Other engines have varied handling, though the overall goal is to limit the influence of low-quality links while preserving link discovery.

Usage notes: In practice, nofollow is commonly applied to blog comments, forums, and other user-generated content areas to deter spam. For paid links and advertisements, rel="sponsored" is preferred. For links created by users, rel="ugc" is recommended. Importantly, nofollow does not guarantee that a link will not be crawled or indexed, and it does not remove the link from the page; for blocking indexing entirely, other methods such as robots meta noindex may be used.