By Shad Super in Questions —

How Do Nofollow Links Affect the Crawling and Indexing Behavior of Search Engines for Linked Content?

Summary

Nofollow links signal search engines to not pass authority or ranking credit to the linked page, impacting the crawling and indexing behavior for linked content. While search engines may still crawl and index the content, the link itself does not influence the ranking of the destination page. Here’s an in-depth exploration of how nofollow links work and their effects on search engine behavior.

A nofollow link is an HTML attribute that webmasters can use to tell search engines that they do not want the link to affect the ranking of the linked webpage. It is created by adding the <rel="nofollow"> attribute to a hyperlink, like so:

<a href="https://example.com" rel="nofollow">Example</a>

This attribute is particularly useful for reducing spam, managing link equity, and indicating that a webmaster does not endorse the linked page.

Nofollow links were introduced by Google in 2005 to combat comment spam in blogs and user-generated content. The goal was to minimize the impact of paid links on search engine rankings and maintain the integrity of their algorithms. More information can be found on Google's Search Central [Qualified Link Guidelines, 2023].

Effects on Crawling and Indexing

Impact on Crawling

Search engines like Google may still crawl and index content linked with a nofollow attribute, although the link itself does not explicitly instruct the search engine to do so. By default, nofollow links indicate that the link should not pass authority to the linked content. However, search engines sometimes crawl these links to discover new content.

Example: If a webpage with a nofollow link to https://example.com is crawled, Google may decide to also crawl https://example.com, but that decision is made independently of the nofollow directive.

Impact on Indexing

While nofollow links do not pass link equity or ranking signals to the destination page, they do not directly prevent a search engine from indexing the content. The linked content can still appear in search results if other signals (such as direct backlinks, content relevance) are strong.

Example: If https://example.com is linked from many pages, even with nofollow attributes, the content might still get indexed if it has other sources of backlinks or significant standalone value.

Practical Implications and Best Practices

Nofollow links are important for maintaining a healthy link profile and complying with search engine guidelines. Excessive use of follow links in sponsored content or paid advertisements can lead to penalties. Using nofollow helps balance link equity distribution on a site.

Example: News websites and platforms like Wikipedia often use nofollow links for user-generated content to prevent the abuse of link equity.

Managing Website Credibility

Nofollow links allow webmasters to control the flow of link equity, ensuring that only trusted and relevant sources receive authority from their site. This practice improves the site's overall credibility and prevents diminishing its ranking potential by "leaking" link equity to low-quality sites.

Search Engine Policies and Updates

Google’s Perspective

Google has specific guidelines and policies on nofollow links. As per the Qualified Link Guidelines, 2023, Google treats nofollow links as hints rather than directives, meaning they may choose to follow such links based on other contextual signals.

Bing’s Approach

Bing also treats nofollow links similarly to Google, using them as a directive to not transfer link equity but may still decide to crawl the linked content based on its own algorithms and signals.

Additional insights can be found on Bing’s Webmaster Guidelines [Webmaster Guidelines, 2023].

Conclusion

Nofollow links play a critical role in modern SEO by allowing webmasters to manage link equity effectively and comply with search engine guidelines. Although they do not pass ranking credit, they do not outright prevent search engines from crawling or indexing the linked pages. By using nofollow links strategically, websites can maintain credibility and avoid penalties associated with unnatural link building practices.

References