Forum Moderators: Robert Charlton & goodroi
Google will continue to support rich snippets for existing content, so you don’t need to redo existing content in the new schema.org format. Changing to the new markup format could be helpful over time because you will be switching to a standard that is accepted across all three companies, but you don’t have to do it.
schema.org is a collaboration by Google, Microsoft, and Yahoo! to improve the web by creating a structured data markup schema supported by major search engines. On-page markup helps search engines understand the information on webpages and provide richer results. A shared markup vocabulary makes it easier for webmasters to decide on a markup schema and get maximum benefit for their efforts.
If you’ve marked up your content for rich snippets using microformats, microdata, or RDFa, then you're already familiar with the process. schema.org works the same way, using the microdata markup format and a vocabulary that is shared by all the search engines and that supports a wide variety of item types and properties....
schema.org supports a wide collection of item types, although not all of these are yet used to create rich snippets.
Why microdata? Why not RDFa or microformats?
Focusing on microdata was a pragmatic decision. Supporting multiple syntaxes makes documentation for webmasters more complex and introduces more overhead in terms of defining new formats. Microformats are concise and easy to understand, but they don't offer an open extensibility mechanism and the reuse of the class tag can cause conflicts with website CSS. RDFa is extensible and very expressive, but the substantial complexity of the language has contributed to slower adoption. Microdata is the most recent well-known standard, created along with HTML5. It strikes a balance between extensibility and simplicity, and is most suitable for building the schema.org....
How does schema.org relate to Facebook Open Graph?
Facebook Open Graph serves its purpose well, but it doesn't provide the detailed information search engines need to improve the user experience. A single web page may have many components, and it may talk about more than one thing. If search engines understand the various components of a page, we can improve our presentation of the data. Even if you mark up your content using the Facebook Open Graph protocol, schema.org provides a mechanism for providing more detail about particular entities on the page....
The Open Graph Protocol enables you to integrate your Web pages into the social graph.... The structured data you provide via the Open Graph Protocol defines how your page will be represented on Facebook.
