After attending a few days at SES London it has become clear that there’s a small, but growing interest in the use of Microformats in the SEO community. A few folks asked me where they can learn more on the subject, to which my answer is: read John Allsop’s (Excellent) Microformats: Empowering Your Markup for Web 2.0.
This post looks at a few small Microformats that you might be using already…
Image credit: Kevin Dooley
Elemental and Compound Microformats
Perhaps you don’t realise that the chances are you’re already using elemental Microformats in your day to day lives as SEO’s. Elemental Microformats can be joined together to create compound Microformats such as hCard, hReview and hEvent. As I write this post, those 3 compound Microformats are the only formats supported (via a not yet fully automated review process, I think) by Google. In this post we examine link based Microformats that do and do not (but perhaps should) have an impact on your search engine rankings.
Rel vs Rev – What’s the difference?
Firstly, there’s a small point to make on the types of attributes you can use for your Microformat rich links. You can insert two attributes into your link and anchor elements: rel=”" or rev=”". According to the rel-faq on the Microformats Wiki,
“rel” describes the relationship of a hyperlink in terms of what the destination (href) is, to the source, or from the source’s perspective. rel=”stylesheet” is perhaps the easiest example to understand in this manner, because it is saying that this resource over there (indicated with the href) is a “stylesheet” for the current document.
Then what does “rev” mean?
Rev indicates a relationship of the linked to document, back to the linked from document. Here’s how they put it at Microformats.org:
“rev” is the precise opposite (or “reverse”) of the “rel” attribute. E.g. a rev=”help” link indicates that the current document is “help” for the resource indicated by the href.
Now we’ve got that point out of the way, let’s take a look at some of the individual Microformats and how they can be applied in a link
The rel=”licence” Microformat is an open format for indicating content licenses which is embeddable in HTML or XHTML, Atom, RSS, and arbitrary XML. This is the standard for which we’re advised to markup Creative Commons attribution. Want to attribute a Flickr image correctly? You could do a lot worse than use ImageCodr, a tool that will choose your licence and mark up the attribution perfectly.
Here’s an example:
This work is licenced under a Creative Commons Licence.
The code for which looks like this:
<a rel="license" href="http://creativecommons.org/licenses/by-nd/2.0/uk/"> <img alt="Creative Commons License" style="border-width:0" src="http://creativecommons.org/images/public/somerights20.png" /> </a><br />This <span xmlns:dc="http://purl.org/dc/elements/1.1/" href="http://purl.org/dc/dcmitype/Text" rel="dc:type">work</span> is licenced under a <a rel="license" href="http://creativecommons.org/licenses/by-nd/2.0/uk/">Creative Commons Licence</a>.
The use of the rel=”nofollow” element is probably one of the most famous and often contentious issues to touch our industry, but did you know rel=”nofollow” is in fact a Microformat, developed in 2005 by Matt Cutts and Jason Shellen? You did? Great! Even back in 2005 rel=”nofollow” was amongst the most frequently (6th most to be exact) occurring “relationship” attributes on the known Internet (Source, Google Code, 2005). This April 2009 post on Linkscape data at SEOmoz found around 2.7% of their index contained nofollowed links.
Votelinks, “vote-for” “vote-abstain” and “vote-against”, represent agreement, abstention or indifference, and disagreement respectively.
In this example, found via the Microformats Wiki page on Votelinks, the “vote for” button uses rev=”vote-for” to indicate the link represents a supporting vote to the page it is linked from (hence the “rev” instead of “rel”):
Here’s what the full code looks like:
<a class="left_value " rev="vote-for" href="/auth/login?dest=http%3A%2F%2Fjyte.com%2Fcl%2Fi-seldom-use-the-shuffle-feature-on-digital-audio-players" rel="nofollow" id="votes_left" style="background-color: pink;"> <span style="color: rgb(255, 255, 255);" id="votes_left_text">4 </span></a>
I’m dubious as to the practical search engine optimisation value of this particular Microformat, although in principle the idea of expressing how far you agree with a page by linking to it is an interesting point.
The rel=”tag” attribute simply indicates that the link is an “author-designated “tag” (or keyword/subject) for the current page”. You’ve got to wonder how the passing of PageRank could be affected by the insertion of this attribute in to your tag cloud links. I’ve never tested for it, and I doubt I’ll ever get time to. Certainly some blog platforms support this format “out of the box” or you can get plugins for platforms such as WordPress that support the rel=”tag” attrbute in their output. Mine doesn’t, although the URL structure of the tag pages indicate what they are.
Here’s an example of rel=”tag” in action taken from the Microformatique blog.
<a href="http://technorati.com/tag/microformats" rel=”tag”>microformats</a>
I think rel=”me” is amongst the most interesting Microformats at the moment. As the Microformats Wiki page states: ” rel=”me” is used on hyperlinks from one page about a person to other pages about that same person”. Why is that important? According to some, Google may well be using this as an indicator for establishing relationships for its Social Search results and that you can use the attribute to create a “social hub on the open web”. Some have observed strange behaviour however. Marshall Kirkpatrick (Editor: ReadWriteWeb) warns his readers to implement the tag carefully to avoid changing the way you rank for your own name.
Google do include this Microformat in their own pages. If you check out the links on my Google profile page, you’ll see each link to my social profiles use the attribute in the external links. I’ve also added it to the links from this blog to my Posterous, Twitter and Linkedin profiles, like this:
<a rel="me" href="http://richardbaxter.posterous.com/">Posterous</a>
By adding rel=”home” to a hyperlink, a page indicates that the destination of that hyperlink is the homepage of the site in which the current page appears. It’s questionable what “SEO value” this one adds, although you could imagine that rel=”home” might be a useful indicator for the canonical version of a homepage (think: default.htm, index.html etc) although (of course) we already have the canonical tag!
Here’s an example, although I’m yet to decide if I’m going to put this on my blog:
<link href="http://seogadget.com" rel="home" />
So, as you can see, elemental Microformats are all around us and you’re probably using some of them already. Where some are more interesting or easier to implement than others, it’s definitely interesting putting some though in to how these attributes could impact the way search engines perceive the links on your pages.
Update 26th May 2010
Rel=”friend”, part of the XFN – The XHTML Friends Network is now being parsed by Google to establish relationships between Facebook accounts:
Here’s the code for that grey rich snippet, highlighted in red:
<a title="Chantal Lulu" rel="friend" href="http://fr.facebook.com/people/Chantal-Lulu/717474542" class="title">Chantal<wbr></wbr> Lulu</a>
Thanks very much to Micheal Cottam for the heads up on this new Google rich snippet feature!
If you’re interested, here’s a complete list of all rel= values that could be inserted into your HTML links.