Congratulations, you've sold your first batch of ads for your blog! You've put together your FTC disclosure (assuming you're blogging in the US) and prepared your special "sponsored post" header for your advertorial pieces, so you're all set to go live with those ads and sponsored posts. Right?
Well, almost. Did you remember to put the rel="nofollow" tag at the end of all the links to your advertiser? If you didn't, you're certainly not alone. This little detail is woefully under-explained and often overlooked, especially by new(ish) bloggers. If you're new to running ads, you may have no idea that you need to use it. But don't worry, I'll get you up to speed today!
rel="nofollow"? What's that?
It's a microformat tag added to the end of a link that instructs search engines not to "follow" the link. When a search engine encounters a "nofollow" link, it does not count the link toward the search engine rank of the target site.
You add rel="nofollow" to a link like so:<a href="http://www.example.com/stuff_for_sale.html" rel="nofollow">My Awesome Sponsor</a>
A nofollow tag does not change what happens when your readers click a link, and the link will not look different to your readers unless they look at your site's source code (nerds like me do that, but we're in the minority).
Why would I make a sponsored link Nofollow?
Despite the complexity and sophistication of their algorithms, search engine robots are kind of dumb. Even if you clearly disclaim your sponsored posts and advertisements in a way that your human readers understand, your robot readers won't know that you've disclosed your paid links unless you use the nofollow tag.
So what? Maybe I don't care what the robots think!
Hey, take it easy on the robots, they mean well! What you do with your paid links is your choice, of course. It's not illegal to leave the nofollow tag off a paid link.
But, it might as well be.
Take a quick look at Google's official policy on paid links so you can make an informed decision about how you'll treat your sponsored links. In summary, Google expects you to either add the rel=nofollow tag to the end of paid links, or redirect the paid links to an intermediate page on your site that's blocked from search engines in your robots.txt file. Many large blogs use some version of the redirect method. But, if you're a small-to-medium blog with a small roster of advertisers, adding the rel="nofollow" tag is the easiest way to comply with Google's instructions.
Other search engines like Yahoo and Bing have different approaches to nofollow and paid links, but since Google's kind of a big deal in the search engine world, it's often in your best interest to listen to their requests.
What about affiliate links?
The short answer is: nobody knows for sure what you're supposed to do with affiliate links. Google has not given an official answer to this question, so it's been left up to the various know-it-alls and kooks of the Internet to figure out for themselves. I've linked to some of the less-kooky discussions in the "further reading" at the bottom of this post.
Update: In June 2012, Google's Matt Cutts gave this answer about nofollow-ing affiliate links:
In summary: Google can recognize affiliate links from most major services, so nofollow-ing those links is not quite as important. But, it doesn't hurt to nofollow them, either.
Do I need to add Nofollow to Adsense links on my blog?
No, Adsense ads do not need a Nofollow tag since they redirect through Google Ad Services and/or Doubleclick before going to the advertiser's site. Many other ad networks work the same way. If you're running banner ads through a network and are not sure if they're redirecting or nofollowing outbound links, check the ad network's documentation or contact them for more info.
Oh no, I'm already running ads without Nofollow! What do I do?
Well, first, don't freak out. This is an easy fix. There are a couple of different ways to do your nofollows. The simplest way is to go through your existing ads and sponsor links and manually add the rel="nofollow" tag to each sponsor's URL. This is time consuming if you have a lot of ads, but it's simple and worthwhile to do.
If you're using a Wordpress plugin to handle your banner ads, that plugin may already take care of your nofollow needs for you. Many advertising plugins either add nofollow to ad URLs automatically or redirect the URLs so you're not directly linking to your advertiser. Check the documentation for your plugin to find out how it handles advertisers' links before you set yourself up for an afternoon of unnecessary work!
There are also Wordpress plugins available that will automatically nofollow all of your outgoing links. You may not necessarily want to nofollow every single outgoing link on your site, though, so this option might not be the best choice for your blog if you have a lot of non-paid, regular links you'd like to keep as-is.
For more on nofollow, including some of the rather heated debate on the subject:
- Wikipedia's entry on Nofollow
- Don't Forget the Nofollow Code When You Sell Advertising from The Work At Home Wife -- this post gets into the potential consequences of not using nofollow, and what to do when a sponsor tells you they don't want a nofollow link.
- Does Google consider affiliate links as "paid links"? A discussion on the Google Webmaster Central forum about handling affiliate links.
- Microformats Made Simple by Emily Lewis explains not only nofollow, but the whole of the world of microformats, an extremely useful and surprisingly fun part of markup. BTW, that's an Amazon affiliate link, and I nofollowed it. Peep my source code to see!