The "nofollow" attribute is an HTML attribute that can be added to a hyperlink to instruct search engines not to follow the link. It was introduced by Google in 2005 as a way to prevent comment spam on blogs and reduce the impact of paid links on search engine rankings.
When a search engine crawler encounters the "nofollow" attribute in a hyperlink, it acknowledges the instruction and does not crawl or index the target page of that link. This means that search engines do not pass any link juice, or ranking authority, from the referring page to the linked page.
However, it's important to note that while search engines generally respect the "nofollow" attribute, it does not guarantee that the link will be completely ignored. Some search engines may still choose to crawl the linked page to some extent, although they do not use it for ranking purposes.
The "nofollow" attribute can be manually added to a link by including the attribute within the HTML code, like this: Anchor Text
Additionally, some content management systems and website platforms may have built-in functionality to automatically add the "nofollow" attribute to certain types of links, such as user-generated content or paid advertisements.