Links are important to SEO, both as positives and as negatives. Using links properly is a huge boon. Using them poorly can earn you some serious penalties and loss of trust. This makes webmasters understandably paranoid about how to use the nofollow attribute, which was introduced by Google to help control the flow of link recommendations and spam.
In the deep recesses of the Google algorithm, one core process rests as the foundation upon which nearly all else is built. This is the link. A link is a vote of confidence from one site to another, in the most general terms. A site with more trust and authority has a higher weighted vote, while a site with low trust and low authority has a nearly valueless vote.
When you link out to another site, the default – at least in past years – is a followed link. A followed link is a link that Google counts. It says to Google that you’re encouraging traffic to consider the destination of the link to be a valuable resource. This is why it’s important for a website to gather an array of relevant authority backlinks.
Unfortunately, this had several problems. What about your blog comments section, where anyone can post a link? A followed link from your domain looks the same regardless of where on the page it was posted. Or what about a case where you link to a site you don’t like, for the purposes of illustration? You don’t want that site to benefit from your link, after all.
The solution to this problem is the nofollow attribute. Adding nofollow to your links makes Google eliminate that vote of confidence. Now you can safely link to your competitors without giving them a ranking boost, and comments sections are now free of spam link – at least, those trying to artificially boost link juice.
So, when you’re linking out, how do you make the choice; should this link be followed or not? Should you just nofollow everything and call it a day?
If you’ve skimmed ahead, you may have noticed that this is the only subtitle with a follow recommendation. That’s because this is a catch-all caveat to your link auditing. See, you have two options when dealing with links on your site. The first is to painstakingly go through every single link on your site and determine on an individual basis whether that link should be nofollowed or not. This is a long process full of research into other websites, types of links and so forth. It’s tedious and, while you may end up with perfectly sculpted links, it might not be worth the time.
The alternative is to take a step back and consider sentiment and purpose. Google wants you to use nofollow to help prevent link abuse and to regulate your marketing links. That’s all. You can be free with your followed links and just follow general guidelines; nofollow advertising links, nofollow links to spam sites and nofollow comment links.
Which path you take is up to you. What follows are tips for specific types of links you can categorically nofollow.
This is a big one, but it often goes over the heads of webmasters who pay more attention to the details and not enough to the reasons. Nofollow affiliate links. Nofollow advertising links. Nofollow links you paid or were paid to get. Nofollow links you post in exchange for a product or service. It seems like a disparate set of rules, but they all fall under one simple banner; any link that has money or a gift in exchange.
Google tries to keep money out of SEO. Of course, money will always have an influence. More money hires more skilled SEO workers. The point is to avoid a world where you can pay X amount of money to reach Y search rank. Any link you use for advertising is a link you should nofollow.
This one is a bit controversial. On one hand, you’re free to make a judgment of trust regarding the sites you link to on your blog. If you don’t trust a site, you have incentive to avoid passing link juice to that site.
On the other hand, what purpose does that link serve? Could you, instead, take a screenshot to illustrate your point? Rather than refer users, take what you need for an example and avoid the link entirely?
There’s also the question of whether you should truly be making the judgment at all. The fact is, you can hurt your site by linking indiscriminately to spam sites, but the penalty is easy to reverse if it occurs. It’s up to you whether you consider the risk worth the time of investigating each site you link to beforehand.
Comments are perhaps the single most exploitable source of links if they’re left followed. Anyone could come to your blog at any time and post a link to any site they wanted in your comments section. This would pass PageRank and lead to the impression that your site supports theirs, when in reality you may not have even noticed the link in the first place.
There are several ways to handle this. The first is a blanket nofollow on all comment links. It’s easy and it’s safe, and it’s what most people do. The second option is to moderate all comments before they appear. This is a good idea in general as well, to make sure you’re filtering out spam comments. A good spam filter can also help with this. A third option is to use a more heavily moderated style of comments, like the Facebook comments plugin.
There has been a lot said about guest blogging this year, ever since Matt Cutts posted his fateful blog entry. Using guest posting to gain links to your site is a bad thing, when done with the express purpose of gaming the system. Otherwise, you’re fine to do so.
Guest post links should follow one simple rule; prune links as you would links in your own posts. If a guest poster submits an article full of links to sites you would never link to, ask for a revision or just remove the links. It’s simple, it’s easy and it solves the nofollow problem.
You can also blanket nofollow any guest post link. It won’t hurt you. On the other hand, there may be the occasional link they include that you’re fine with following. Feel free to follow those links; they’re legitimate enough anyway.
In general, just nofollow any link you wouldn’t recommend to a friend. That’s all links are, really; recommendations to your followers that they should read the site in question.