RDFa stands for Resource Description Framework-in attributes and provides a set of XHTML attributes to enhance visual data with machine-readable hints. This standard originates to tackle today’s web which has been built predominantly for human consumption. Even as machine-readable data begins to appear on the web, it is typically distributed in a separate file, with a separate format, and very limited correspondence between the human and machine versions. As a result, web browsers can provide only minimal assistance to humans in parsing and processing web data: browsers only see presentation information.

With RDFa we can embed rich metadata within XHTML documents. This metadata has the form of RDF triples User-Predicate-Object. Some examples of RDFa attributes are the following:

  • about and src – a URI or curie specifying the resource the metadata is about
  • rel and rev – specifying a relationship or reverse-relationship with another resource
  • href and resource – specifying the partner resource
  • property – specifying a property for the content of an element
  • content – optional attribute that overrides the content of the element when using the property attribute
  • datatype – optional attribute that specifies the datatype of text specified for use with the property attribute
  • typeof – optional attribute that specifies the RDF type(s) of the subject (the resource that the metadata is about).

Users can easily combine there attributres with other schemas such as FOAF into web pages in order to build rich compelling social sites. For example,  an event on a web page can be directly imported into a user’s desktop calendar.  A photo’s creator, camera setting information, resolution, and topic can be published as easily as the original photo itself, enabling structured search and sharing. Geo location can be embedded so that users can easily track authors of articles.

RDFa has demonstrate quite an impressive growth in recent years. New research released by Yahoo! shows that RDFa demonstrated explosive growth in 2010 as the  fastest growing data markup format on the Web, and is used on more than 430 million web pages. It accounts for roughly 3.6% of the all of the Web pages on the Internet. How much did RDFa grow last year? 510% .


1. http://rdfa.info/

2. http://www.w3.org/TR/xhtml-rdfa-scenarios/

3. http://en.wikipedia.org/wiki/RDFa

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