What does nofollow mean in SEO?

nofollow is a name given to certain types of backlinks. I include a link on this page to Amazon but, in the code I mark it nofollow. What's the reason and is there some magic formula which says that a certain percentage of backlinks to a website should be 'nofollow'?

What does nofollow tell a search engine?

Let's get the biggest misunderstanding out the way. It does not tell search engines "Don't follow that link" and even if it did they would say "Mind your own business and don't tell us what to do and where we can go".

To understand nofollow you need to understand the role of backlinks in SEO. Every page on every website has a certain amount of link juice available to give out.

Some of that link juice might be because another website out there links to it. Some because the domain name is quite old and the content has been stable. This site has been on the Internet for the long game, not for "here today, gone tomorrow" purposes. There is an argument that user behavior plays a role. If users react positively to a page by staying longer it gets more brownie points but this is not agreed by everyone.

Link Juice is really a measure of how much a search engine like Google trusts you to deliver quality content. It trusts Wikipedia a lot and it has reached that conclusion because a zillion people link to it or mention it every day and it sees the content is carefully moderated, not filled with spam and links to crappy websites.

And this link juice is a major factor that search engines use when deciding who should rank at the top of the search results.

So Wikipedia has buckets of link juice so often comes up at the top of the SERPs. It also means it has buckets of link juice to dole out.

The original thinking behind the link juice concept was that webmasters would only link to other webmasters if they were basically recommending the other webmasters content. But what about if you are condemning it or simply want to make an objective observation? Or what if you run a website where members get to post content, like on a forum or in blog comments? Someone might want to put a link to a website there but you don't want to say that you as the webmaster recommend it in any way.

You don't want to pass on link juice which will help the other websites rankings.

This is where nofollow comes in. It says to search engines "Don't allow any of my link juice to follow this link".

How you define a link as nofollow

In many platforms like Wordpress you don't need any coding experience. When you add a link you simply have to tick a box stating it is a nofollow link.

If you're looking for it in the source code of a webpage it looks something like this:
<a href="http://yoursite.com" rel="nofollow">Link Text</a>

The rising popularity of nofollow

Because backlinks are important some webmasters used to hire armies of people to troll round places like forums and blog comments looking for ways to lever in a link. The kind of webmasters that hired those kinds of people usually had pretty poor content and that was why they needed to game their way to the top.

Computer software was even developed that could crawl the web and add links wherever possible.

These link building activities became so overwhelming for some directories, forums and blogs that they just started marking all links nofollow so the spammers would lose interest. The message is "you can add a comment here and you can even include a link to your site but it will not help your site's rankings". It was enough to put some spammers off bothering.

Then Google said that if it found a lot of these links to spammy sites or completely unrelated sites on your website it would be you who got penalized which could mean losing all or some of your rankings. But because the exact definition of what you shouldn't link to was vague a vast number of webmasters hit the panic button and marked all their links 'nofollow', even ones they truly recommended.

The general reaction in the SEO community was pretty over the top. I never added 'nofollow' to any additional links at the time on any of my websites or any of my clients websites. If they weren't marked nofollow already it was because they were links to genuinely useful and complementary information on whatever topic the page was about.

After a while things calmed down a bit but you'll still find most places such as forums and article comments sections mark any links posted as nofollow by default.

Should some of the links to your website be nofollow?

Despite nofollow links passing on no link juice and having no direct SEO benefit a number of Search Engine Optimizers started claiming you should have some in order to make your overall backlink profile look 'natural'.

A 'natural' website, they claimed, would have normal links (often called dofollow links) and nofollow links. After some lengthy studying of top ranking websites they started coming out with actual numbers such as 40% of your backlinks should be 'nofollow'.

This is the kind of crazy connection that would make us all conclude stalks bring babies. Yes, websites which rank top for competitive keywords will often have a mix of dofollow and nofollow but we're usually talking here about hundreds or thousands of links. So yes of you have thousands of links and they are all dofollow that doesn't look natural.

But for your standard website with perhaps a few dozen backlinks there is nothing unnatural if all of them are dofollow. By sheer default if you do start ranking well and receiving a lot of traffic some of those visitors are going to mention you on forums and in blog comments and as your number of backlinks continue to grow the mix will pan out naturally.

So no follow links are a way for a webmaster to say to search engines, "Don't let any of my link juice follow that way". For historical reasons they have become the default link type on most forums and in most comments sections. But you don't need to have them. They are not a magic way of making your backlink profile look more natural and so avoid a Google penalty.

Just concentrate on getting two types of backlinks. Dofollow links from good quality websites with some link juice to share. Nofollow links that are likely to bring you good quality traffic like well put together listings in respected directories.