"Nofollow" provides a way for webmasters to tell search engines "Don't follow links on this page" or "Don't follow this specific link."
nofollow attribute appeared in the page-level meta tag, and instructed search engines not to follow (i.e., crawl) any outgoing links on the page. For example:
<meta name="robots" content="nofollow" />
nofollow was used on individual links, preventing robots from following individual links on a page required a great deal of effort (for example, redirecting the link to a URL blocked in robots.txt). That's why the
nofollow attribute value of the
rel attribute was created. This gives webmasters more granular control: instead of telling search engines and bots not to follow any links on the page, it lets you easily instruct robots not to crawl a specific link. For example:
<a href="signin.php" rel="nofollow">sign in</a>
How does Google handle nofollowed links?
In general, we don't follow them. This means that Google does not transfer PageRank or anchor text across these links. Essentially, using
nofollow causes us to drop the target links from our overall graph of the web. However, the target pages may still appear in our index if other sites link to them without using
nofollow, or if the URLs are submitted to Google in a Sitemap. Also, it's important to note that other search engines may handle
nofollow in slightly different ways.
What are Google's policies and some specific examples of nofollow usage?
Here are some cases in which you might want to consider using
- Untrusted content: If you can't or don't want to vouch for the content of pages you link to from your site — for example, untrusted user comments or guestbook entries — you should nofollow those links. This can discourage spammers from targeting your site, and will help keep your site from inadvertently passing PageRank to bad neighborhoods on the web. In particular, comment spammers may decide not to target a specific content management system or blog service if they can see that untrusted links in that service are nofollowed. If you want to recognize and reward trustworthy contributors, you could decide to automatically or manually remove the
nofollowattribute on links posted by members or users who have consistently made high-quality contributions over time.
- Paid links: A site's ranking in Google search results is partly based on analysis of those sites that link to it. In order to prevent paid links from influencing search results and negatively impacting users, we urge webmasters use
nofollowon such links. Search engine guidelines require machine-readable disclosure of paid links in the same way that consumers online and offline appreciate disclosure of paid relationships (for example, a full-page newspaper ad may be headed by the word "Advertisement"). More information on Google's stance on paid links.
- Crawl prioritization: Search engine robots can't sign in or register as a member on your forum, so there's no reason to invite Googlebot to follow "register here" or "sign in" links. Using
nofollowon these links enables Googlebot to crawl other pages you'd prefer to see in Google's index. However, a solid information architecture — intuitive navigation, user- and search-engine-friendly URLs, and so on — is likely to be a far more productive use of resources than focusing on crawl prioritization via nofollowed links.
How does nofollow work with the Social Graph API (rel="nofollow me")?
If you host user profiles and allow users to link to other profiles on the web, we encourage you to mark those links with the rel="me" microformat so that they can be made available through the Social Graph API. For example:
<a href="http://blog.example.com" rel="me">My blog</a>
However, because these links are user-generated and may sometimes point to untrusted pages, we recommend that these links be marked with nofollow. For example:
<a href="http://blog.example.com" rel="me nofollow">My blog</a>
rel="me nofollow", Google will continue to treat the
rel="nofollow" as expected for search purposes, such as not transferring PageRank. However, for the Social Graph API, we will count the
rel="me" link even when included with a
To prevent crawling of a rel="me nofollow" URL, you can use robots.txt. Standard robots.txt exclusion rules are respected by both Googlebot and the Social Graph API.