Links add value to the page they link to. However, this is sometimes not desirable. Using the follow/nofollow attribute, search engine robots are instructed whether to follow a link with this attribute or not. This affects search engine optimization in relation to link attributes precisely when backlinks should be "devalued" in terms of their algorithmic impact on page rankings.
Since 2005, bots from Google and other search engine providers have been able to deal with rel="nofollow".
Background, meaning, and purpose of nofollow
In the early days of the Internet, backlinks were more important than search engines for navigating the WWW, because in the early and mid-1990s they were not as important as they are today, and their indexes were only a small fraction of today's storage performance. However, in order to gradually improve these metrics, it was especially important that bots were able to follow outbound links on the website in order to quickly navigate to other websites.
With the increasing competition for search engine rankings, the backlink has finally got a completely new dimension. Link popularity has become an important quantitative ranking criterion: the more backlinks, the better the ranking.
The door to search engine spam was wide open. Search engine optimizers and webmasters installed backlinks through link farms, link exchanges, bookmarking services, and often it was done automatically through software. It didn’t matter at the time whether the backlink was set up for advertising purposes or not.
Fighting link spam, link farms, file sharing networks, and fake blog comments
Thus, websites with big capital in the background could buy high quality and strong backlinks by placing advertisements on appropriately popular and trustworthy websites of daily newspapers or news networks. That was a situation that Google, of course, didn't really like. But it was impossible to prevent large publishers from linking from other sites.
To finally end this hustle and give webmasters the ability to devalue links, Google, along with Yahoo and Microsoft, introduced the so-called nofollow attribute. Links from blog comments are now often called nofollow, and thus dried up as a source of valuable backlinks for link spammers.
This is what the nofollow attribute looks like
If you select one link, it looks like this:
If you don't want the bot to follow links on the website, it looks like this:
The attribute is then part of the meta tags.
Attention: the presence of the nofollow attribute in the meta information does not mean that the corresponding page is not indexed! If you want the bot not to follow the links on the crawled page and to index this page, you need to use the following tag:
Alternatively, the bot can be instructed to follow the links, but not to index the content:
Where is nofollow used?
The following uses are possible with the nofollow attribute:
- Preventing spam in blog comments
- Advertising labeling
- Linking from unreliable sites to illustrate the situation, in order to avoid the danger of bad neighborhood
Note: You can often read on SEO forums that the nofollow attribute can be used to generate PageRank or target link juice control. Output links or other "unimportant" pages could be excluded from crawling, and the link juice can flow more strongly to pages with actual content.
However, it is often not taken into account that nofollow links only interrupt the natural flow of PageRank and are not saved for other backlinks. In general, rel ="nofollow" should not be used to indicate internal links, except in justified exceptional cases.
Do nofollow links affect rankings?
Again and again, the question arises whether nofollow links or many of them can affect the page ranking. Google's top spam guard, Matt Cutts, commented on this in an interview (see also video below) and confirmed that nofollow links do not affect the rankings.
The consequence of this statement would be that you should not exchange links with sites that have backlinks with the nofollow attribute. However, it can be assumed that this statement by Matt Cutts does not tell the whole truth:
First, it doesn't take into account that a backlink from a highly visited, high-quality and trustworthy site can also deliver traffic, i.e. visitors. And second, the nofollow links in the link profile seem to signal a certain “naturalness”. So avoiding this entirely would be a mistake.
Google Webmaster video with Matt Cutts about the topic:
The Site Experience in the Searchmetrcis Suite offers the ability to query the number of URL web pages indexed. The Index vs Noindex section has an overview of all crawled URLs, their index and tracking status.
The Searchmetrics Suite distinguishes 4 categories:
- Index-Follow: These pages are indexed by the respective search engine and the crawler is instructed to follow all the links on the page. This is the default setting, even if you don't specify it in the code.
- Index-Nofollow: These pages are in the index. However, the crawler is instructed not to follow the links on the page. A blog article can be called an example of the use of this attribute, which does appear in the index, but you should not follow the links in the blog comments, so as not to affect the ranking.
Noindex-Follow: These pages are excluded from indexing. However, the crawler is instructed to follow the links on the page. It makes sense to use it, for example, with duplicate category pages that should not be included in the index, but for which the search engine should still track the content.
- Noindex-Nofollow: These pages are excluded from indexing, and the crawler is instructed not to follow the links on the page. This instruction is useful, for example, for pages with custom content.
The overview chart is followed by a table in the bottom half of the page that lists the individual pages crawled and provides detailed indexing and tracking status information. Information about the number of outgoing/incoming links, as well as the SPS and CheiRank can also be displayed.