By Shad Super in Questions —

What Role Do Nofollow Links Play in the Spidering Process?

Summary

Nofollow links instruct search engine crawlers not to follow or influence the ranking of the linked page in their algorithms. This guide explores their role in the spidering process, including definitions, history, functionality, and specific use cases.

Definition and Usage

A nofollow attribute, written as <a href="URL" rel="nofollow">, is added to a hyperlink to signal search engines not to follow the link. It was created primarily to combat spam in comments and untrusted user-generated content [Google Support, 2023].

History and Evolution

The concept of nofollow links was introduced by Google in 2005, in collaboration with other major search engines, to help webmasters control outbound link equity [Preventing Comment Spam, 2005]. Over time, its usage has expanded to various scenarios, including preventing paid links from passing PageRank and managing site crawling budgets.

Functionality in the Spidering Process

Influence on PageRank

Nofollow links do not pass link equity, meaning they do not contribute to the PageRank of the linked page. This helps maintain the integrity of search engine algorithms by preventing manipulation through paid or low-quality links [Google Developers, 2023].

Crawling Behavior

While nofollow links do not contribute to rankings, search engines may still crawl them. Google, for example, treats the nofollow attribute as a hint rather than a directive, which means it may choose to follow such links for discovery purposes, but won't necessarily pass link equity [Evolving Nofollow – New Ways Google Handles Nofollow, 2019].

Specific Use Cases

Combatting Comment Spam

Nofollow links are widely used in comment sections and forums to prevent spammers from gaining undeserved search engine ranking benefits through link drops [WordStream, 2023].

Search engines like Google advise using the nofollow attribute for links associated with paid advertisements or sponsored content to avoid penalties for violating their link schemes policies [Link Schemes, 2023].

Untrusted Content

Nofollow links are also useful for linking to untrusted or questionable content, ensuring that the link does not inadvertently benefit such content in search rankings [Moz, 2023].

Below is an example of how to use a nofollow link in HTML:

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

Conclusion

Nofollow links play a crucial role in managing how search engines crawl and index the web, preventing link-based manipulation and maintaining the quality of search results. They are particularly important in user-generated content, advertising, and untrusted content scenarios.

References