Without complex decision trees helping computers determine what pieces of text relate to what, it's nearly impossible to make use of the wealth of data available on the web.
In the case where you're only interested in people reading your pages, that's fine. But what if you want other sites to access and use the data you're offering with a full understanding of the context? We're one step closer to a standard that defines exactly how to make this clear.
HTML + RDFa Working Draft Released
Using RDFa, authors can embed data meant for machine consumption (say, meta-data regarding the sources for an article) while simultaneously making that data viewable for human consumption.
An entire section of this document relates to changes that would have to be made for the HTML 5 specification in order to fully support RDFa. The two changes discussed involve ensuring that all RDFa attributes and values are conforming to HTML 5 and XHTML 5, and that attributes involving CURIE prefix mappings (an abbreviated syntax for expressing URIs) conform to HTML 5, though they already conform to XHTML 5.
Why the Excitement?
Obviously a computer can scrape the same information from the page without needing anything fancy like RDFa, but the program does so without any understanding of context. At times you may not care. Maybe you're just writing a blog post and wanted to share something interesting with friends.
Yet, even a quick blog post has RDFa applications. Let's look at an example that takes us back to the idea of citing a source for an article. You could just include a link, like so:
Or, you could make it clear that you are actually citing this link as the article's source to programs that look for RDFa metadata. You do this by adding a rel statement in your link HTML like so:
<a rel="cite" href="http://www.w3.org/TR/2009/WD-rdfa-in-html-20091015/">HTML+RDFa</a>
Now, search engines and other programs that have code to process RDFa might list you automatically has having written a post that cites this particular work.
Of course, this example barely touches on the real power of RDFa and the semantic web. The team working on Drupal 7 is already looking at the future and putting their imaginations to work on how to make use of such technologies. So should you.