When running a website, there are instances where unintended links to external web pages are placed in areas where anyone can post, such as comment sections or forums. In these cases, it is recommended to appropriately convey the relationship with the linked website to search engines. This article explains the background and usage scenarios of the “nofollow” attribute, which is used to indicate the relationship with external links, for SEO managers.
What is a nofollow link?
nofollow is used to prevent search engine crawlers, such as Google, from following a link.
(Figure 1: Treatment of standard links and links with nofollow by search engines is different)
There are two ways to use it depending on the purpose. In both cases, there is no visual difference between regular links and these links on the web page. It is solely a directive for search engines.
— Use it as one of the values in the “rel” attribute of the <a> tag
The following is the description. It can be used to instruct Google not to follow the link set in the <a> tag. In this usage, ‘nofollow’ is positioned as one of the values of the rel attribute. Other values besides ‘nofollow’ will be explained later in this article.
— Use it as one of the directives specified in the “robots” meta tag
By using nofollow in the robots meta tag, written in the <head> section, you can instruct Google not to follow any of the links on that web page. An example of this usage is shown below.
Related Articles: What are Meta Tags?
Background of the Introduction of nofollow
Both methods mentioned are used to prevent Google from following links, but the introduction of nofollow also addresses the issue of spam.
One of the reasons Google gained attention as a search engine was the introduction of an algorithm called PageRank, which reflects the connections between pages (links) in its rankings. This system allowed Google to significantly outperform other search engines of the time, which primarily relied on whether a keyword was included as an important signal.
However, when Google publicly disclosed the details of PageRank, link spam began to proliferate, exploiting the algorithm to manipulate rankings. For example, people would try to improve their search rankings by generating external links in places like blog comment sections and message boards, where anyone could post URLs.
As these practices became widespread, undeserving web pages started to get evaluations. To combat this, Google introduced nofollow. By setting nofollow on links placed in areas where anyone can post, website administrators can signal to Google that these are not intentionally placed links. When Google recognizes nofollow, it will not follow the link, and the link will not affect the evaluation of the web page.
Source: Official Google Blog: Preventing comment spam
Specific examples of links that should not be followed
— Links within User-Generated Content (UGC)
An aspect influencing the background is the inclusion of links within user-generated content. This specifically refers to comments, forum posts, and similar contributions. If a website includes such functionality, the “ugc” value within the rel attribute is used.
— Paid links such as advertisements
Google guidelines also mandate distinguishing between advertisement links within a website and other links. This is to prevent potential adverse effects on search result rankings if these links are treated the same as regular ones. When monetary transactions or similar exchanges are involved in link placement, the “sponsored” value within the rel attribute is used.
Source: Spam policies for Google web search
— Links embedded within elements difficult to control
When utilizing embedded content such as widgets from other sites, the links contained therein may not always align with desired preferences. In such cases where control is challenging, it’s advisable to use “nofollow” for these links.
Source: Qualify your outbound links to Google
Values usable in the “rel” attribute of the <a> tag
Values usable in the “rel” attribute of the <a> tag are used to convey the relationship with the linked web page and to indicate to Google when links shouldn’t be followed. If a link should be followed unconditionally by Google, there’s no need to specify the “rel” attribute.
As there are multiple values available for the “rel” attribute besides “nofollow,” it’s advisable to set the appropriate attribute for each type of link:
— rel=“sponsored”
Used for advertisements or paid links (links involving monetary transactions for placement)
— rel=“ugc”
Used for links within user-generated content (UGC) such as comments or forum posts.
— rel=“nofollow”
Used when there are no other suitable values for the link, when you don’t want to associate the link with the site, or when you want to prevent crawling of the linked page from your site.
It’s also possible to use multiple values for links that are both UGC and sponsored.
Source: Qualify your outbound links to Google
— “sponsored” and “ugc” were released in 2019
Attributes conveying the relationship of links were limited to “nofollow” for a long time, but in September 2019, new values such as “sponsored” and “ugc” were added. Additionally, in March 2020, the treatment of “nofollow” was changed from a directive to a hint.
During this change, there was a notification that websites already using “nofollow” for paid links or UGC didn’t need to update the values. Therefore, many existing websites continue to use only “nofollow.”
For future links that qualify as sponsored or UGC, it’s recommended to use these values.
Source: Evolving “nofollow” – new ways to identify the nature of links
Points to watch regarding the use of nofollow
— Nofollow is treated as a hint
Nofollow and similar values have been treated as hints since 2019. While Google typically doesn’t follow these links, it’s important to recognize that they are ignored as hints rather than directives.
— Pages linked with nofollow may still be crawled if discovered through other sources
Since it only discourages crawling from the linking page, pages with nofollow links may still be crawled if discovered through other sources, such as when linked from other web pages.
— Use robots.txt to control internal link crawling
While some websites may have used nofollow in the past to control internal link crawling, Google recommends using robots.txt for this purpose. If nofollow is used for controlling crawling, it’s advisable to reconsider and utilize robots.txt instead.
Summary
This article covered nofollow, which can convey the relationship with external links and discourage crawling. For user-generated content (UGC), paid links, and external links that are not intentionally placed, it’s important to use nofollow, ugc, or sponsored to properly convey the relationship to search engines.
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