Nofollow

Nofollow, rel="nofollow", is a link attribute asking search engines not to treat a link as a vote for the page it points to.

It dates from 2005. Since 2020 Google treats it as a hint rather than a directive, and offers rel="sponsored" and rel="ugc" for paid and user-generated links.

A nofollow link can still send valuable visitors; whether a backlink is worth having is better judged by the traffic it sends.