A nofollow link is a hyperlink that does not influence the search engine ranking of the destination page. This is because it contains a rel=”nofollow” HTML attribute that signals to search engines that the destination page should not be crawled. Taking the “crawl” hyperlink in the previous sentence as an example, the link would be considered a nofollow if the HTML looked like this:
<a href="https://www.webopedia.com/definitions/web-crawler/" rel="nofollow">crawl</a>
In 2020, Google clarified its stance on nofollow links, stating that this attribute is considered more of a suggestion or recommendation than an explicit instruction of the site’s webmaster. This is a pivot from Google’s earlier protocol in which a nofollow attribute was observed at the webmaster’s behest.
As mentioned above, dofollow links are ones that do not include a nofollow HTML attribute. This is the most common type of link, especially because an author usually places a hyperlink to intentionally direct traffic to another site. Backlinking with dofollow links for a reputable destination page is a favorable practice for search engine optimization (SEO), so there are very few instances when an author would include a hyperlink that they do not want a search engine to acknowledge.
Nofollow links, on the other hand, are less common because they need to be specified in the HTML. The only exceptions to this are pages that have a nofollow meta tag in the HTML header, which automatically applies the nofollow function to all links contained in the body content. (These implementations have become less common over time as web design and content creation have become more strategic.) Many content management systems (CMS) also add nofollow HTML attributes to links in comments by default so that the main page’s search engine rankings aren’t hindered by spam links.
Although less common than dofollow links, nofollow links have historically served a meaningful purpose in a few specific use cases.
When a visitor to a site places a link in a comment or discussion board post, the link is considered UGC along with the rest of the post. A significant portion of UGC is spam, so a nofollow attribute in this case prevents a spam link from degrading the SEO of the host’s website. A dofollow link should only be used if the user’s contribution is trustworthy and reputable.
(Note: In 2019, Google announced the addition of the rel=”ugc nofollow” attribute to distinguish this type of content from other nofollow instances. This distinction is useful for separating genuine UGC from spam even though the link might not warrant editorial endorsement.)
When a webmaster includes a link on a page in exchange for money or goods/services, the link is considered to be sponsored. These links should be identified in the content of the post per FTC guidelines (example: “This post contains affiliate links.”) as well as the HTML of the link itself to avoid suspicion of link scheming, where links are used to manipulate a page’s SERP ranking.
This is when nofollow attributes come in handy. If a hyperlink’s HTML includes the nofollow attribute (or more specifically as of 2019, a rel=”sponsored nofollow” attribute), it discloses to the search engine that the webmaster is including the link because they’re being compensated to do so. The link isn’t earned, unlike dofollow links, and is disclosed as such to avoid negative consequences.
On some occasions, a webmaster may link to a page without wanting to be affiliated with it from a search perspective. For example, if a blog about ice cream links to a blog about cheese because of a dairy-related news item, the link would make sense in context of the article content but search engines might not recognize this connection at the HTML level. A nofollow link in this case would prevent a search engine from penalizing the ice cream blog for including a seemingly irrelevant link about cheese that could be seen as part of a link building campaign. Similarly, if there’s any question about a destination site’s credibility, a nofollow attribute minimizes the risk of being associated with an untrustworthy domain.
In general, nofollow links don’t hurt search engine optimization (SEO), but they don’t directly benefit SEO either. Instead, they mitigate SEO consequences of links that could be considered spam or part of a link scheme. To use an analogy, a nofollow attribute applied to a link is to SEO what a picture covering a scuff is to the wall on which it’s hanging. The picture itself doesn’t inherently make the wall more valuable, nor does it fix the scuff, but it does prevent the wall from being denigrated because of the scuff.
There are, however, exceptions to this rule. Several studies have demonstrated that search engines will sometimes follow links despite the presence of a nofollow attribute, though it’s unclear what criteria create these exceptions. To this effect, Google says that links marked with “rel” attributes will generally not be followed, but does not specify conditions that fall under the “general” category or otherwise.