RDFa is an extension to HTML5 that helps you markup things like People, Places, Events, Recipes and Reviews. Search Engines and Web Services use this markup to generate better search listings and give you better visibility on the Web, so that people can find your website more easily.
The Web Data Commons project extracts structured data from the Common Crawl, the largest web corpus available to the public, and provides the extracted data for public download in order to support researchers and companies in exploiting the wealth of information that is available on the Web.
E. Najmi, Z. Malik, K. Hashmi, and A. Rezgui. Information and Communication Systems (ICICS), 2016 7th International Conference on, page 145--150. IEEE, (2016)