What’s structured data?
Unless you’ve been living under a rock for the past two years, you’ll be all over “rich snippets” – those fabulous little search results that help you stand out from the crowd in your organic rankings. Structured data added to web pages helps search engines parse your data into different types of search results, like recipe search. Review ratings, events, recipes, company names, contact name, job titles and even friend connections on Facebook have at some stage been visible in the search results for “white listed” web sites.
Making the right choice on the use of markup
In Google’s words, “adding markup is much harder if every search engine asks for data in a different way.” – this is so true. For webmasters making the difficult decision on which markup to choose has been quite a hurdle. The simplicity of Microformats over the depth and creativity of RDFa, or the HTML5 working group approved Microdata? What about the RDF/XML based Goodrelations for ecommerce?
It seems the search engines have made that choice for us by introducing a new, standardised collaboration called schema.org.
read more on …http://www.seomoz.org/blog/schemaorg-a-new-approach-to-structured-data-for-seo