In the interests of starting with a bold statement, I'll go with what I twittered earlier this morning:

My seo theory for the morning. Nofollow is dying.

During SES last week, I had the chance to talk to a few people about a trend we believe we are seeing in Google's treatment of two big trends on the web. You can't have failed to have spotted the growth of Twitter recently. Some people have started blogging less as a result of the ease and adoption of Twitter (and other similar "status update" micro-blogging platforms such as Facebook status updates). Many people have a greater reach on Twitter than they do via their blog and they certainly have more tools to make it easy to post thoughts, discoveries and questions.

This isn't another Twitter post though - it's about the impact on SEO of this evolving use of the web. In the same way that blogging, commenting, trackbacks (and associated spam) forced a change in the search engines' strategies, I believe we are starting to see similar changes caused by this new shift.

The effects that I intend to dig into a bit deeper are:

• Explosion of publishing on 3rd party platforms
• Increasing use of nofollow for a range of purposes

I believe that the combination of these trends has profound implications in the optimal way of constructing a search engine - something Google cares a great deal about. Not only that, but we are seeing the beginnings of the effects my theory predicts.

Publishing on 3rd party platforms

You will find advice in many places about best practices for blogging URLs. In order of preference for SEO from top to bottom, you would prefer:

1. www.example.com/blog
2. blog.example.com
3. www.exampleblog.com (when your main website is example.com)
4. example.wordpress.com (or .blogspot.com etc.)
5. thirdpartydomain.com/example
6. thirdpartydomain.com/examplepost1, thirdpartydomain.com/examplepost2 etc.

There are two main factors making #1 the right answer:

1. Ensuring your link-worthy content acquires links to your main website
2. Having all your content on a domain you control
   

Although we have seen many blogs created as sub-domains of 3rd party domains (such as *.blogspot.com), there is no overwhelming trend towards this and no fundamental reason why anyone would recommend it. With Twitter (as short-hand for any social service allowing micro-updates), however, not only is there no choice but to publish on a 3rd party domain, but with Twitter especially, many many people are creating link-worthy content scattered across that domain (like option #6 above). This is resulting in a massive number of links to twitter.com (see its position on the SEOmoz top domains list) and incredibly well-linked profiles (as internal links on Twitter such as @willcritchlow are nonofo).

[Incidentally, who would have thought that you could really create link-worthy content in 140 characters? Well, it turns out you can - anything that gets re-tweeted is essentially proving its linkworthiness - see below.]

Imagine for a second that instead of Twitter.com, the thing becoming hugely popular was micro-blogging software (a kind of Wordpress for Twitter). So we were seeing the current growth in usage, but instead of being www.twitter.com/stephenfry, Mr. Fry was posting his updates at www.stephenfry.com/twitter - but apart from that, the usage was the same. Individuals could choose to remove the nofollow from their links to their friends and other sites. We would be seeing an explosion in creation of hugely-interlinked small pages - a change to the layout of the internet as big the explosion in blogging a few years ago. We are seeing this change - but it's all happening at Twitter.com.

Increasing use of nofollow for a range of purposes

Google lists the three main intended uses of nofollow as:

1. Linking to untrusted content
2. Paid links
3. Crawl prioritisation (typically linking to yourself with nofollow)

Leaving aside for a second the ability / likelihood of webmasters using nofollow correctly (which means that the search engines need to work even with broken implementations just as they often rank HTML code that doesn't validate), there are two big uses of nofollow that are breaking the model:

1. Complete "silo-isation" of large sites
2. Domain owner not trusting trusted content authors' links

"Silo-isation"

Disregarding the fact that I just made that word up, there is a very real trend of powerful sites nofollowing all (or nearly all) outbound links even though they are the very definition of editorial links. The site owners have presumably seen the ranking power achieved by Wikipedia nofollowing all outbound links and are trying to form their very own black hole.

Lack of trust

My understanding of the original intent of proffering nofollow as a solution to the problem of linking to untrusted places was that it was mainly intended for situations like blog comments, profile links, etc., where users of your site could create links to wherever they pleased.

This is definitely valuable (as anyone who has ever had to moderate blog comments can attest) but what about once you do trust the commenter? Since so many sites have no mechanism whereby that nofollow is ever removed, we end up in a situation where people are creating huge amounts of really valuable content and the links they create are nofollow.

In my opinion, some of the most "valuable" links on the internet at the moment are nofollow. Some examples:

• The average quality of outbound links from Wikipedia is incredibly high
• Many people are leaving their RSS feed readers untouched and getting their news via links their friends drop on Twitter
• We know many sites whose biggest sources of traffic after search are links which happen to be nofollow (leading to interesting discussion of the effects on the random surfer model)
  

After posting my provocative theory on Twitter this morning, I asked people to show me some great links via the #nofollowisdead hashtag and I found some things I really wanted to read, including:

• A mention of me I hadn't seen before! From Carlos del Rio (whose book, User Driven Change, is out now - I read it when it was still a draft and I highly recommend it)
• All customers are liars (warning: some strong language!) via Wiep
• Possibly the coolest new blog I've seen in some time - 1000 Awesome Things via Hannah

Obviously this is a dreadful test, but I think it is a strong example - I find many of the most interesting things I read every day via my network.

So what does this mean?

I believe that just as the search engines have acknowledged the limits of webmaster declaration of untrusted or paid content and often downgrade links they believe should have been nofollow, I believe they have to acknowledge the limits in the other direction as well. In other words, some nofollow links should be followed. In the interests of finding the best content for their searchers, search engines are increasingly going to have to use their own (algorithmic) judgment to disregard some nofollows and include those links in their link graph.

Theories are all well and good, but we have also seen the first signs that this is actually happening. We have seen tests where new sites with only nofollow links to them are ranking. The most powerful example was the speed with which a new site (admittedly an exact match domain name) whose first link was from Wikipedia was indexed and began ranking - even before acquiring any subsequent links.

Agree? Disagree? Think it's already happening? Think it's never going to happen? I'd love to hear your thoughts in the comments.

If you liked this, you might like link building is not just for SEO that Rob here at Distilled wrote last week.