Schema. org is an initiative launched on 2 June 2011 by Bing, Google and Yahoo! (the operators of the then world’s largest search engines) to “create and support a common set of schemas for structured data markup on web pages. ” On 1 November Yandex (whose search engine is the largest one in Russia) joined the initiative. They propose using their schemas and Microdata in HTML5 to mark up website content with metadata about itself.