edit Aliza Earnshaw on June 1, 2011
edit "No follow" links tell search engines not to bother
When you attach the NoFollow attribute to a link on your site, you’re telling search engines that you don’t trust the page the link goes to – the target page – or you don’t think the target page will be valuable for people to find in search results.
When the NoFollow attribute is not present, it’s like telling search engines that you trust the linked page and feel its content is valuable to searchers. You’re saying it’s perfectly all right for search engines to add the page to their indexes.
The HTML coding for the NoFollow attribute looks like this:
<a href="http://TargetWebPage.com" rel="nofollow">anchor text for link</a>
In the above example, the URL for the target page is represented by targetwebpage.com, and the text used for the link is represented by anchor text for link.
By the way, most search engine optimization (SEO) professionals commonly refer to "nofollow" rather than "no follow." We like CamelCasing at AboutUs - we feel it helps readability - so we refer to the attribute as NoFollow. A link that does not have the NoFollow attribute is often called a DoFollow link.
edit Contrary to popular myth, there’s almost no SEO benefit to marking internal links NoFollow.
To understand this technique, you need to know that web pages can be graded according to a ranking Google uses, called PageRank, after Google co-founder Larry Page. A higher PageRank indicates that a web page is more important, relative to other pages on the Web. PageRank is all about the number and quality of links pointing to that web page.
Google determines how important a page is largely by how many other pages link to it, and whether the links come from pages that themselves have high authority. Within a website, Google figures that any page with lots of links from other pages on the site must be important.
Links on high-authority pages pass SEO goodness – often called “link juice” – to the linked page, which can help the page’s PageRank, and its rankings in search results. If a webmaster had a number of links on a specific web page, but wanted to concentrate the link juice on one particular target page, he would add the NoFollow attribute to the other links. All the SEO goodness would then pass through the single DoFollow link to its target page.
edit PageRank sculpting no longer works.
In 2008 Google announced it would divide PageRank equally among all the links on a page, whether they’re NoFollow links or DoFollow. That means any link on a page can pass no more than its own allotted fraction of PageRank.
Many people still believe they can control the flow of PageRank, or SEO value, through the use of the NoFollow attribute. They can’t.
To learn more about PageRank, read What PageRank Means for Your Website.
edit The proper use of NoFollow on your site is for making the best use of search robots’ time.
In general, it’s best to refrain from using NoFollow on internal links – that is, links that go to other pages on your site. That’s because you probably want Google and other search engines to add most pages on your site to their indexes.
However, you may want to use NoFollow to ask search engine robots to refrain from crawling links to pages that you don’t think need to show up in search – for example, links to log-in pages. A search engine robot can spend only a given amount of time crawling each page on your site. So it makes sense to make the best use of the robot’s time by adding the NoFollow attribute when a link points to a page that you don’t need people to find in search results.
Remember that NoFollowing a link doesn’t guarantee search engines won’t add the target page to their indexes. First of all, some search engines do follow all links, disregarding the NoFollow attribute, to discover new pages and add them to their indexes. And you can’t prevent other websites from linking to a page you have marked NoFollow.
edit NoFollow is appropriate for external links in user-generated content.
If you have a section of your site where visitors can add comments and links, you should NoFollow those links. That’s because you probably can’t take the time to vet every link added by visitors, to make sure you trust the sites they are linking to. NoFollowing links added by visitors – and being public about this – also discourages spammers from using your site to drive more traffic to their own sites.
If you link to other sites – and you should if those sites are relevant to your website and your visitors – you should allow those links to be DoFollow.
The exception to this is paid links. If someone pays you to include a link to their site – for example, an affiliate partner or an advertiser – you should use the NoFollow attribute on those links. For more information about why, you can read Google’s guidelines on paid links.
You can get DoFollow links from AboutUs.org by editing your Website Profile to make it useful to AboutUs.org visitors. Learn more about our DoFollow policy.