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Matt Cutts on Nofollow and the Siloing Solution

by Virginia Nussey, June 15, 2009

At Search Marketing Expo - SMX Advanced in Seattle last month, Matt Cutts, head of Google's anti-spam team, said that nofollow-based "PageRank sculpting" was less effective than in the past. SEOs were left wondering how the change would affect their optimization efforts. As a panelist during the second day of the search engine marketing conference, Bruce Clay wanted to gauge the scope of the issue. "How many people in the audience are using nofollow?" he asked. The show of hands was practically unanimous.

Update: Shortly after the publication of this article, Matt Cutts published a post on his blog further explaining Google's recommendations for using the nofollow attribute. We have updated this article to include Matt's most recent indications of how nofollow affects PageRank. While the recordings in the article accurately document what Matt said at SMX Advanced, additional details are addressed in Matt's blog post, PageRank sculpting. Bruce Clay will be offering further analysis and recommendations regarding nofollow on the June 24th episode of SEM Synergy.

In the years since the link element was first introduced, many Web site optimizers have come to use rel="nofollow" to limit the transfer of PageRank through internal links on a site. PageRank (PR) is an important indicator of authority used by Google to rank pages in search engine results. PageRank sculpting involves including a nofollow element on links to internal pages not targeted for ranking in search engines. By directing PR only to theme landing pages, SEOs try to concentrate PageRank on pages best positioned to rank for targeted queries. This technique is a small part of the themed site architecture methodology known as siloing, discussed in more depth later.

Since nearly every advanced SEO uses the nofollow attribute on internal links, the Internet marketing community was eager for clarification following Matt's initial comments. Attendees of this year's SMX Advanced conference had a chance to ask for further explanation during the You&A with Matt Cutts. Those not at the conference relied on second-hand accounts to inform them of what was being said. However, Bruce made a personal recording of the question and answer session, and because we feel that Matt's specific comments offer valuable insight on the matter, we're glad to be able to report parts of it here.

With that said, let's start at the beginning.

Where's the PageRank Going?

 Matt Cutts on PR Evaporation
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Question: Hey Matt, just to get back to PageRank sculpting for a second, you had mentioned that if you had 10 links on the home page and five of them you made nofollow so there were only five left, it used to be that the remaining PageRank would be kinda distributed amongst those remaining five.

Matt Cutts: Correct

Question: Now you're saying that that's changed and that's not really happening, so there is some kind of a loss of PageRank. Where is it going?

Matt Cutts: You can almost think of it as just evaporating.

In this exchange, Matt used the word "evaporate" to illustrate what happens to PageRank on a page that has nofollow links. Later in the session Matt further explains, "A little bit of it evaporates and then the rest goes out in the outlinks, and it essentially mimics a random surfer clicking around on the Web." In his blog post, Matt says that PageRank evaporation due to the use of nofollow has been going on for more than a year:

Originally, the five links without nofollow would have flowed two points of PageRank each (in essence, the nofollowed links didn't count toward the denominator when dividing PageRank by the outdegree of the page). More than a year ago, Google changed how the PageRank flows so that the five links without nofollow would flow one point of PageRank each.

In a comment on the post, Matt explains that "this is a change that's been live for well over a year; if you've got a site that works for you and you're happy with, I wouldn't worry about going back to change a lot of work."

Regardless of when the change was implemented, SEOs are left with the question, "So, what does evaporate mean?" When Bruce, an SEO who has listened to and analyzed search engine rhetoric for more than a decade, heard Matt's comments at SMX Advanced, he interpreted "evaporate" as a small loss. However, in reading Matt's blog post, it appears that PageRank evaporation may be more significant. According to Matt's example, one can interpret that there is a total loss of PageRank associated with nofollow links.

Matt says that PageRank evaporation due to nofollow has been occurring for more than a year. About a year ago Bruce noticed that PageRank was being lost due to nofollow links, so he sent Matt an email and asked if Google was doing this intentionally. Matt subsequently replied that the issue was being worked on, and Bruce later observed that the unexpected behavior had stopped. If Bruce was in fact witnessing the new behavior of the nofollow element, internal testing suggested that PageRank evaporation came and left. When it became a permanent change is anyone's guess.

Should SEOs Rule Out PageRank Sculpting?

Matt provided some helpful clarification about PageRank evaporation, but how does that affect the tactic of PageRank sculpting? Again, let's turn to Matt.

 Matt Cutts on PR Sculpting
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Matt Cutts: So I think some people ran some experiments early on and they're like, "Ah ha! I can use nofollow like a scalpel. I can send all my PageRank to these pages, the pages that I want to be crawled, and ignore these contact forms or these login pages, so I can shunt my PageRank where I want it to go." And that's less effective these days. It's not going to get you a penalty, you're not going to get in trouble. Google's not going to say, "Oh, he's in trouble for using links with no follow, in the clink!" or anything like that. However, it's not as effective. So, it's definitely a better use of your time to go and make new content.

The other thing that I would say, which is pretty simple, is, if you're using nofollow to change how PageRank flows within your site, it's almost like a band-aid. It's better to make your site the way you want PageRank to flow from the beginning, and then it's good for users and it's good for search engines. So, how you choose to link within your site is your own business, and I would tell people, you can try to sculpt PageRank, but it's not going to be as useful.

According to Matt Cutts, PR sculpting may not be worth it. SEOs now have to contend with at least two reasons why PageRank sculpting is a largely inefficient use of resources. First, most pages on the Web have a low level of PageRank and a high number of outbound links. In this scenario, when the nofollow attribute is used on a handful of links, only a small amount of additional PageRank is allocated. The potential PageRank gain is worth arguably less than the effort required to implement PageRank sculpting. Second, pages lose PR when the nofollow attribute is used. Together these two facts support Matt's statement that PageRank sculpting may not be the best use of time. Matt said that use of the nofollow element isn't a negative indicator, so SEOs don't have to throw it out of their toolbox altogether, but he recommends a judicious application of the link element. There are many reasons not to pass PageRank internally if you can help it, but Matt says a better solution is to architect a site so that it flows PageRank as intended.

Siloing: An Architecture Supported Solution

At Bruce Clay, Inc. we teach and use a theme-supported architecture methodology called siloing. Siloing involves the creation of theme-based sections of a site, known as silos, and linking practices where support pages link to same-silo landing pages. By implementing siloing through a site's directory structure and internal links, PageRank will be distributed primarily to a site's main landing pages. In teaching siloing, Bruce recommends using the nofollow attribute internally only when linking to non-landing pages across theme boundaries. Did Matt address this strategic use? He did.

 Matt Cutts on Nofollow for Theming
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Question: So you want to theme them but you're gonna link from one theme into another. Well does it make sense to use rel="nofollow" in that type of a case?

Matt Cutts: If it's an internal link, our rule of thumb is, you know, you know it, you know the source page, you know the destination page, you know that you trust both pages, I would not use nofollow in most cases. That's my new rule of thumb because, you know, you've maybe got one page in the good directory and some subdirectory. You've got another page, and they're all available to your user, so there's no reason to add a nofollow to that. Typically it's for a link that you don't want to vouch for, and those tend to be third-party links, the user-generated links, the ones that are posted by other people on external sites rather than your internal site.

Nofollow was originally introduced as a way to indicate a link to an untrusted site. However, search engines have since redefined nofollow as a way to stop PageRank transfer. Matt seems to be suggesting a preference for the original use of nofollow, but by saying "most cases" he's leaving the door open for nofollow on internal links. The problem for SEOs is that frequent cross-theme linking eliminates theme boundaries, and then the site may not be considered a clear subject matter expert on the queried theme. After Matt's most recent comments, Bruce will continue to recommend a selective, cautious and educated use of nofollow to delineate a site's distinct themes.

When Does Matt Say Nofollow is Appropriate?

 Matt Cutts on Themed Architecture
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What we've been saying from the beginning is don't spend as much of your time on the PR sculpting aspect of it. Spend your time on making good site architecture so PageRank just flows wherever you want. And so that's why we've been saying, use it sparingly, use it for links you can't vouch for, use it for user generated content that you don't necessarily trust, and this is all up on the HTML documentation page we made for rel="nofollow", and the last one that we mention, and we barely mention it, is if you are a power user and there's a specific page you don't want, like a sign up page or a login page, that's a fine way to use nofollow. For example, if you look on my site, if you look on my blog, mattcutts.com, I don't have, you know, I have an About Me page, I have, you know, I don't know if I have a copyright page, but I wouldn't put a privacy or a copyright page, I wouldn't put a nofollow on that. The only thing I have nofollow on, on my blog, I believe, is my subscribe link and that's because it goes to an RSS feed, which is really not all that useful for a main Web index.

Again Matt emphasizes that site architecture is the best way to direct PageRank. He also mentions nofollow on links to sign up and login pages, pages that are often an SEO's target for nofollow links. Matt refers to Google's rel="nofollow" help documentation and says that experienced SEOs, or "power users", are welcome to use the nofollow attribute on a "specific page you don't want" and on links that aren't useful in a main Web index. In other words, it's okay to use nofollow to direct bots away from pages you don't want ranked.

It's worth noting here that the nofollow attribute is not the only tool SEOs have for limiting PageRank transfer. Bruce recommends using an iframe to remove blocks of links from a page. The iframe gets the links off the page, making the page code cleaner and easier for spiders to crawl. Alternately, search engines don't pass PageRank through HTML form constructs - considered the original nofollow attribute. Nofollow is a convenient way to direct the flow of PageRank through a site, but there are alternatives that can do the job effectively. If using nofollow is your only option, no need to be concerned. Nofollow still accomplishes the three things it always has.

Nofollow Still Does the 3 Things You Want it To

  1. The nofollow attribute prevents the pass of PageRank to pages not related in theme and pages not targeted to rank.
  2. The nofollow attribute helps delineate theme boundaries, ensuring that the Web site is not seen as generic by search engines.
  3. The nofollow attribute directs the flow of PageRank. By focusing PageRank on landing pages, an SEO can help propel a page's ranking.

After hearing what Matt had to say on the use of the nofollow element and PageRank sculpting, we hope it's easier to put the issue in perspective. Don't dwell on the PageRank you're losing from nofollow, but instead remember what you're gaining with a strategic internal link structure. As a stand-alone practice, PageRank sculpting is a band-aid not supported by site architecture. The most comprehensive link management strategy integrates theme-based site architecture aligned to the way people search. And that's the beauty of siloing.

Those who have been part of the SEO community since 2003 may recall a similar environment of chaos and confusion following the Florida Update. Google was essentially recalibrating PageRank values, and the immediate result was a significant rankings drop for many top-performing sites. In the resulting rumor-rich climate, some SEOs speculated that Google was penalizing sites that were optimized. When PageRank values were restored within weeks, the only ones still feeling the pain were webmasters who "deoptimized" their sites due to misunderstanding and fear.

We would encourage the SEO community not to react in kind to the now-infamous Seattle Update. Approach the use of nofollow with caution rather than abstinence and avoid a knee-jerk reaction. Google will continue to change their models and preferences, and Matt Cutts will continue to change his message to stay inline with company objectives. It's obviously in Google's best interest not to have their PageRank algorithm manipulated. They rely on the quality of search results to retain loyal users, in turn drawing advertisers and ad revenue. Looking at it from a search engine's point of view may be helpful when interpreting Google's intent.

As for webmasters and SEOs, if Matt's post is true, this change happened more than a year ago. So, if your site is doing well today, you have almost no cause for concern. Use nofollow cautiously and track site rankings for a few months before drastically altering your site. Remember that your goal is traffic and conversion. So long as those remain steady, you'll ride out this storm and return to clear waters. And remember, if it ain't broke, don't fix it.


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