Structured data makes your site's content easy to re-use and display in useful ways. It does this by adding information around fields. If you are new to structured data and RDF, the following video gives an introduction to the basic RDF concepts.
Some Uses of RDF
RDF is a network effect technology—the more people there are using RDF, the more useful it becomes. Here are some current users of RDF.
- Google Rich Snippets
If you use specific RDF on your pages, Google can display your search results in a more informative and attractive way. Different studies have shown these results have 15-30% higher click-through rate.
- Facebook's Open Graph
Facebook uses RDFa to enable the 'like' button that people can put on their site. When a user clicks this 'like' button, information about the external Web page shows on the Facebook user's stream and may also be included on their profile.
- BBC's Wildlife Finder
Wildlife Finder uses the RDF version of Wikipedia as the data backend for some of it's content. That means that when the BBC team needs to correct a factual inaccuracy, they correct it in Wikipedia instead of on their own site, so the work contributes to a global effort. It also means that the BBC benefits from the work of people outside their team. The Wildlife Finder also exposes it's data.
DBpedia exposes Wikipedia's structured content so that it can be queried with SPARQL. They also provide an interface for exploring data about resources, for instance structured data in Wikipedia about Drupal.
RDFa in Drupal
By default, Drupal uses RDFa, which is RDF in HTML attributes. For instance, if a page has information about a person named Jane Doe, it could be represented in RDFa like this:
<div typeof="foaf:Person"> <h2 property="foaf:name">Jane Doe</h2> </div>
The node is mapped to an RDF type, 'foaf:Person', and the title is mapped to an RDF property, 'foaf:name'.
There are default mappings for some entities, used on properties like title and date created. These defaults are inserted automatically into the markup when the module is enabled.
The RDF Mappings API allows you to define your own mappings for content types and to alter existing mappings.