What is Nofollow?
What does nofollow mean?
Early 2005 Google announced that hyperlinks (a clickable link to a webpage) with the rel="nofollow" attribute would not be counted as a backlink for the purposes of PageRank or influence the target sites ranking in the search engine.
Its intent was to reduce the value of spam, made by people and bots (an automated program) spamming comments on blogs and forums.
It also meant that the website owner could tell the Google crawler (which is a computer program that gathers information on the Internet) what links they didn't want followed from their site.
How this attribute is interpreted by the likes of Yahoo, Bing, MSN Search and others, differs between each search engine.
Some may take it literally and not follow the link, others will follow and index the target page but not give weight to the link. While some, such as Ask.com, ignore the attribute completely. They just go on through as if it doesn't exist.
Originally, the nofollow was written as meta tag in the header information and instructed search engines not to crawl all of the outgoing links on the page.
<meta name="robots" content="nofollow">
Later the nofollow attribute was nested in individual links. So rather than instruct the robot s not to follow all the links on the webpage, it could instruct them not to follow a specific link.
<a href="signin.php" rel="nofollow">sign in</a>
You'd use the nofollow attribute if you don't want to vouch for the content of the page that you're linking to. Or if you can't, because the link is posted to the page in the comments or guestbook.
Robots can't sign in or register on a forum, so there's little reason to invite a search engine bot to follow "sign in" or "register here" links.
Using nofollow encourages the Googlebot to crawl the other pages quicker, those you'd prefer to see indexed in Google's database.
This repurposing of the nofollow attribute to force crawl prioritization is an attempt to
control internal PageRank flow it is known as "PageRank Sculpting".
It's a controversial practice that has been challenged by some SEO professionals, And Google itself have urged Webmasters not to focus on manipulating internal PageRank. While they don't encourage it, they won't frown upon it (interesting to note, YouTube a site owned by Google, uses nofollow on internal pages such as the 'share' and 'help' links).
As yet there is no published evidence that proves either effectiveness or harm in using nofollow in such a way.
Another way that nofollow has been repurposed has been in the practice of paid links.
A webpage's ranking in search results is partly based on the number of other webpages that link to it.
That can be artificially influenced by people paying for links. Buying a link at a popular, well trafficked or highly ranked site. To prevent this Google urges webmasters to use nofollow on thse links. Search engine guidelines require disclosure of paid links.
Both PageRank Sculpting and Paid Links are highly controversial and open for heated debate. This article only touches on both topics, while not taking a particular side or having an opinion. I suggest you do more research into it if you're considering doing either.
Nofollow on HubPages
HubPages implements nofollow on their internal links. They also impose it on hubs, depending on certain criteria.
Any individual hub that is below a HubScore of 40 has all outbound links (yes, the ones that you've put in there too) nofollowed.
A HubberScore (that's the score of the author) of below 75 causes ALL the outbound links on ALL your hubs to be nofollowed.
That means that if an author is publishing hubs for the primary purpose of promoting their own other sites, the SEO effect will be worth zero. However if an author makes an effort to publish original content and not be overly promotional, they should be fine.
There is also nofollow on fan links. When one person fans another their link shows up in the profile page of the person that they've fanned.
Initially this is nofollowed. However if the fanning is reciprocated (they become mutual fans) the fan page links become followed.
This is to prevent (or at least reduce) any advantage that may be gained from "fan spamming"