Google wants you to use structured data markup on your site to give it better information, and help it make more compelling search results.
"If Google understands the markup on your pages, it can use this information to add rich snippets and other features to your search result," the company explains. "For example, the search snippet for a restaurant might show its average review and price range. You can add structured data to your page using the schema.org vocabulary and formats such as Microdata and RDF, alongside other approaches such as Microformats. You can also add structured data by tagging the data on your page using Data Highlighter."
Google doesn't, however, want you to use this markup in spammy ways, which people have obviously been doing.
Google is now reportedly sending webmasters abusing rich snippet markup notifications of manual actions taken on their sites. Search Engine Roundtable points to a Google Webmaster Help forum post where one webmaster shared a message they received:
Spammy structured markup
Markup on some pages on this site appears to use techniques such as marking up content that is invisible to users, marking up irrelevant or misleading content, and/or other manipulative behavior that violates Google's Rich Snippet Quality guidelines.
The webmaster who posted it said his team couldn't find the issue. Suggestions from others in the discussion included marking up his name as the author in three different ways on a page, marking up things that aren't visible on the page, marking up one item as both an article and a blog post, marking up empty space in the footer, and marking up a Facebook page as a publisher of the webpage.
Maybe we'll get a Matt Cutts video on the subject soon.
Image via Google