Search engines including Bing, Google and Yandex rely on special tagging to improve the display of search results, making it easier for people to find your web pages and products.
Many applications, especially search engines, can benefit greatly from direct access to structured data. On-page tagging enables search engines to understand the information on your web pages and provide richer search results in order to make it easier for users to find relevant information about your site and products.
Other consumer services such as Facebook and Pinterest also use this data for richer display of your pages and products, in order for their users to find relevant information about your site and products.
??Tagging comes in 3 flavors: oEmbed (Pinterest), Open Graph (Facebook), and Schema.org (Search Engines). It is recommended to implement all three versions.