By Shad Super in Questions —

How Does the "Nofollow" Attribute on Site Links Affect Google's Crawling and Indexing Process?

Summary

The "nofollow" attribute signals to search engines like Google that a hyperlink should not influence the ranking of the link's target in the search engine's index. It is primarily used to prevent spam and control the flow of page authority. However, it doesn't completely prevent Google from crawling or indexing the linked page.

Understanding the "nofollow" Attribute

What Is "nofollow"?

The "nofollow" attribute, used within an anchor tag ([Wikipedia, 2023]), is an instruction to search engines that certain links should not affect the target's ranking in the search engine's index. It is applied by adding rel="nofollow" to an HTML anchor tag.

Purpose of "nofollow"

This attribute was introduced by Google in 2005 to combat spam, especially in comments and forums, and to provide webmasters control over the way links on their sites pass "link juice" or page ranking authority [Google Search Central, 2023].

Impact on Crawling and Indexing

While "nofollow" links do not pass PageRank, they may still be crawled and indexed by Google. The "nofollow" attribute tells Google not to pass on the link metric to the target page, but it doesn't act as a directive to block the search engine from crawling the link [Search Engine Journal, 2020].

Crawling Behavior

Google may choose to crawl "nofollow" links for discovery purposes. This means that while the link itself does not influence the ranking of the linked page, the page can still be indexed if Google deems it relevant [Google Webmaster Blog, 2019].

Indexing Considerations

The presence of "nofollow" does not guarantee that the linked page will remain unindexed. If other non-"nofollow" links point to the page, or if the page is otherwise discoverable, it can still be indexed by search engines [Google Developers Blog, 2019].

Use Cases for "nofollow"

Preventing Spam

One of the primary uses of "nofollow" is to prevent spam, particularly in user-generated content like comments. By not passing authority, it discourages spammers from linking to their sites from comment sections [Moz, 2023].

Google recommends using "nofollow" for paid or sponsored links to ensure compliance with their link schemes policies, preventing these links from artificially boosting a site's ranking [Google Search Central, 2023].

User-Generated Content

For content that is user-generated and not trusted, applying "nofollow" ensures that the links do not inadvertently endorse the linked pages [Google Support, 2023].

Conclusion

While the "nofollow" attribute prevents the passing of link authority to the linked page, it does not entirely block Google from crawling or indexing the page. It remains an essential tool for webmasters to control the flow of link equity and to manage user-generated content effectively.

References